CAUSATION IN ENGLISH TORT LAW: STILL WRONG
AFTER ALL THESE YEARS
SANDY STEEL*
To the question – when may a claimant recover substantial damages from a
defendant despite being unable to prove that the defendant’s wrongful conduct caused
her damage? – English tort law gives an incoherent and unjust answer. After briefly
outlining that answer in the first part of this article, the second part describes some
fundamental aspects of its incoherence and injustice. It traces each aspect to the House
of Lords decision in Fairchild v Glenhaven Funeral Services Ltd,1 the modern source
of English tort law’s enclave of exceptional proof of causation rules. If the charges of
incoherence and injustice against Fairchild are well-founded, it amply deserves a place
in this special issue. The third part of the article sets out what the law on proof of
causation in tort should have been had it not been distorted by Fairchild and its
progeny.
I THE CURRENT LAW
We can state the law on proof of causation in English tort law as follows.
(1) The claimant generally bears the legal burden of proof to demonstrate on
the balance of probability that the defendant’s wrongful conduct was a cause of
its damage in order to recover substantial damages.2 This will involve
demonstrating on the balance of probability that but for the defendant’s wrongful
conduct, the damage would not have occurred or that the defendant’s wrongful
conduct materially contributed to the damage.3 The legal burden of proof dictates
that if a finding cannot be made as to the existence or non-existence of some fact
according to the governing standard of proof, the party bearing the burden fails to
establish the relevant fact. Consequently, as a general rule, if it is impossible to
demonstrate that the defendant was a cause of the damage on the balance of
*
1
2
3
Lecturer in Law, King’s College London. Email: [email protected].
[2003] 1 AC 32 (Fairchild).
Cf. e.g. Sienkiewicz v Greif (UK) Ltd. [2011] UKSC 10 (Sienkiewicz): ‘It is a basic principle
of the law of tort that the claimant will only have a cause of action if he can prove, on the
balance of probabilities, that the defendant’s tortious conduct caused the damage in respect
of which compensation is claimed.’ [16] per Lord Phillips; see also [138] per Lord Rodger
(describing this as the ‘usual’ rule); [184] per Lord Brown and [197] per Lord Kerr (both
describing it as the ‘normal’ rule).
Some cases use the language of ‘material contribution’ in circumstances where it would be
perfectly possible to say that but for D’s wrongful conduct, (part of) C’s damage would not
have occurred. In such cases, the language of ‘material contribution’ is unnecessary and
obfuscating. See, on this: S H Bailey, ‘Causation in Negligence: What is a Material
Contribution?’ (2010) 30 Legal Studies 167. There is, however, a non-redundant concept of
‘material contribution’ according to which D materially contributes to C’s damage if and
only if D’s wrongful conduct played a more than minimal role in a mechanism which was
causally sufficient for the claimant’s damage. For a more precise analysis of the nonredundant concept, see S Steel and D J Ibbetson, ‘More Grief on Uncertain Causation in
Tort’ [2011] 70 Cambridge Law Journal 451.
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probability, the allocation of the burden of proof dictates that the claimant loses
on the causal issue.
(2)
The claimant is exceptionally relieved of proving that the defendant
caused her damage on the balance of probability where the claimant suffers from
mesothelioma (an asbestos-induced cancer) and it is impossible, due to the
limitations of medical science, to determine on the balance of probability whether
or not the defendant’s wrongful conduct was a cause of the claimant’s
mesothelioma and all potential causes of the claimant’s mesothelioma would
operate to cause mesothelioma in a substantially similar way. In such
circumstances, C may establish that D is liable in damages for C’s mesothelioma
simply by showing that D’s wrongful conduct has materially increased the risk of
C contracting mesothelioma.
This exception to the general rule was established by the decision in
Fairchild. Fairchild involved three claims in each of which an employee had
been wrongfully exposed to asbestos dust by successive employers and had either
died or suffered from mesothelioma. Each employee had, on the balance of
probability, contracted mesothelioma as a result of wrongful conduct, but was
unable to prove on the balance of probability which employer’s or employers’
wrongful conduct had been causative because of limitations of scientific
knowledge over the mechanism by which mesothelioma is caused. It was and
continues to be unknown whether the disease is caused by a very small number of
fibres or by the cumulative effect of many fibres. Consequently, each defendant
could argue that the claimant’s disease had been caused by a small number of
fibres for which another defendant was responsible. The House of Lords allowed
the estates of the deceased employees and the only living employee to succeed
against each defendant on the basis that each had materially increased the
employee’s risk of mesothelioma.4 In the later case of Barker v Corus (UK) Ltd.,
which involved the same facts as Fairchild except that the claimant’s
mesothelioma may have been caused by his contributorily negligent exposure to
asbestos whilst self-employed, the House of Lords held that D’s liability in
damages in situations to which the decision in Fairchild applies is proportionate
to the risk to which D wrongfully exposed C.5 According to Barker, if D
wrongfully exposed C to a 20% risk of mesothelioma and the mesothelioma
caused C £50,000 of loss, C should recover £10,000 from D. Parliament very
soon after reversed the apportionment of liability made in Barker, but only in
cases of mesothelioma caused by asbestos, with Section 3 of the Compensation
Act 2006.6
4
5
6
Fairchild v Glenhaven Funeral Services Ltd [2003] 1 AC 32. Although the employees in
Fairchild were accepted to have been the victims of a complete tort on the balance of
probability (i.e. one or more defendants had wrongfully caused the employee’s
mesothelioma) and so all the potential causes of the employee’s mesothelioma were
wrongful, the decision was not limited to such situations. Rather, Fairchild was premised
upon the earlier decision of McGhee v National Coal Board, 1973 SC (HL) 37; [1973] 1
WLR 1, where C suffered dermatitis either through dust attacking his skin non-wrongfully
whilst at work or through D employer’s wrongful failure to provide showers. Already, then,
from the decision in Fairchild, it was difficult to argue that it could be restricted to cases
where all potential causes of C’s damage were wrongful. See further, below, pp 245-246.
Barker v Corus (UK) Ltd. [2006] 2 AC 572.
Section 3 of the Compensation Act 2006 entitled ‘Mesothelioma: Damages’ states at Section
3(1) that ‘This section applies where — (a) a person ( ‘the responsible person’) has
negligently or in breach of statutory duty caused or permitted another person ( ‘the victim’)
to be exposed to asbestos, (b) the victim has contracted mesothelioma as a result of exposure
to asbestos, (c) because of the nature of mesothelioma and the state of medical science, it is
not possible to determine with certainty whether it was the exposure mentioned in paragraph
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(3)
The most difficult question is whether the claimant is exceptionally
relieved of proving that the defendant caused her damage on the balance of
probability in cases where the damage suffered is not mesothelioma. It is likely
that there are two further situations in which this will be so under the decision in
Fairchild. In both situations the defendant’s liability will be proportionate to the
level of risk it has wrongfully imposed upon the claimant. This is because the
decision in Barker v Corus (UK) Ltd. continues to apply to any non-mesothelioma
cases which fall within the decision in Fairchild. The first situation is where D
wrongfully exposes C to a toxic agent or wrongfully fails to protect C against a
risk posed by a toxic agent, which conduct materially increases C’s risk of
contracting a disease, C suffers from the disease, and the aetiology of the disease
is such that it is impossible to determine whether or not the wrongful risk
imposition caused C’s disease, where all potential causes of C’s disease operate in
a substantially similar way, and the defendant is not the National Health Service.7
The second is where C has been the victim of a tort which has caused C to suffer
an injury and it is impossible for C to demonstrate on the balance of probability
which of a number of defendants, each of whom, in breach of a duty, has
materially increased the risk of that injury to C. Call this last situation the
‘indeterminate wrongdoer situation’.
There are at least three reasons to believe that Fairchild will apply in the
first situation. First, the House of Lords in Fairchild considered that the earlier
House of Lords decision in McGhee v National Coal Board was, properly
interpreted, an authority supporting the decision in Fairchild.8 In McGhee, the
claimant could not prove whether his employer’s failure to provide showers to
wash off brick dust after working in the employer’s brick kilns had caused his
dermatitis. The uncertainty over the contraction of dermatitis was structurally
similar to the uncertainty in Fairchild: the medical evidence did not permit one to
determine whether a few dust particles cause the disease or whether a large
number of dust particles acting in combination cause the disease. So Fairchild is
likely to apply to dermatitis, at least on the assumption that medical
understanding has not advanced since McGhee.9 Secondly, the Court of Appeal
has applied Fairchild, albeit unnecessarily, since a finding of but-for causation
could probably have been made, in a case involving Vibration White Finger
disease.10 Thirdly, in the recent Supreme Court decision in Sienkiewicz v Greif
7
8
9
10
(a) or another exposure which caused the victim to become ill, and (d) the responsible person
is liable in tort, by virtue of the exposure mentioned in paragraph (a), in connection with
damage caused to the victim by the disease (whether by reason of having materially
increased a risk or for any other reason).’ Section 3(2) then provides that: ‘The responsible
person shall be liable— (a) in respect of the whole of the damage caused to the victim by the
disease (irrespective of whether the victim was also exposed to asbestos—(i) other than by
the responsible person, whether or not in circumstances in which another person has liability
in tort, or (ii) by the responsible person in circumstances in which he has no liability in tort),
and (b) jointly and severally with any other responsible person’.
It seems clear that Fairchild cannot apply in the medical negligence context in claims against
the N.H.S: see Gregg v Scott [2005] 2 AC 176 at [85], [90] per Lord Hoffmann and at [225]
per Lady Hale; Barker v Corus [2006] 2 AC 572 at [39] per Lord Hoffmann.
Fairchild, [2003] 1 AC 32 [21], [33] per Lord Bingham.
McGhee was criticised in obiter remarks in Sienkiewicz, above n 2, by Lord Phillips [92] and
Lord Brown [177]. These obiter remarks do not alter the fact that McGhee was treated as an
important authority for the decision in Fairchild.
Brown v Corus (UK) Ltd. [2004] PIQR P30, [2004] EWCA Civ 374. See also the earlier
obiter dicta in Transco v Griggs [2003] EWCA 564 at [35] per Hale LJ that Fairchild
applied in a Vibratory White Finger case and the view of Smith LJ in Novartis (Grimsby)
Ltd. v Cookson [2007] EWCA Civ 1261 that Fairchild could not be applied to bladder
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(UK) Ltd., a mesothelioma case involving a wrongful exposure of an employee to
asbestos dust by an employer and non-wrongful exposure due to asbestos present
naturally in the environment, Lord Phillips and Lord Rodger, with whom the
other seven Justices agreed, considered that the Fairchild decision was justified
by the ‘rock of uncertainty’ faced by mesothelioma claimants, given the available
scientific evidence over the aetiology of the disease.11 This tends to suggest that if
similar impenetrable uncertainty surrounded the aetiology of another disease then
the Fairchild decision would apply to it.12 It is impossible, however, to be
confident as to this. The inference is only justified so long as it is reasonable to
expect judges to decide cases in accordance with an identifiable legal principle.
As we shall see, that expectation may not be rational in the proof of causation
context.
The approval by the House of Lords in Fairchild of the decisions in the
Californian case of Summers v Tice13 and the Canadian case of Cook v Lewis14
supports the claim that Fairchild will also apply in the indeterminate wrongdoer
situation. Summers and Cook both involved a claimant who had been negligently
shot by a hunter but, because another negligent hunter had fired at the same time
as the causative shot, it was impossible to determine which hunter had causatively
wronged the claimant: both concerned the indeterminate wrongdoer situation.
Secondly, Lord Phillips in Sienkiewicz suggested that Fairchild would apply in an
indeterminate wrongdoer situation.15
II INCOHERENCE AND INJUSTICE IN THE LAW
The current law is incoherent in two main respects. First, the reasons offered by
judges to explain the law do not explain it. Secondly, the way in which the law
conceptualises exceptions to proof of causation on the balance of probability does not
accurately describe the legal nature of those exceptions. It is not necessary to think that
‘coherence’ in the law is intrinsically valuable to find each of these problematic.16
Rather, the consequences of the incoherence are (also) regrettable. If the reasons
11
12
13
14
15
16
cancer because it was not ‘analogous to mesothelioma’ [70] (implicitly accepting, then, that
an analogy could be made to mesothelioma in cases of other diseases). It is true that
Fairchild has also not been applied in cases which do not involve mesothelioma. But these
cases are readily explicable that in Fairchild was not applicable for some reason other than
simply that the disease was not mesothelioma. This is true of: Sanderson v Hull [2008]
EWCA Civ 1211 (the uncertainty over causation was not due to the lack of scientific
knowledge); Clough v First Choice Holidays and Flights Ltd. [2006] EWCA Civ 15 (the
same as Sanderson); AB v Ministry of Defence [2012] UKSC 9 (there were multiple different
possible causative agents).
Sienkiewicz [2011] UKSC 10 [133] per Lord Rodger; at [97], [103] per Lord Phillips; [200]
per Lord Kerr.
Admittedly, Lord Brown attempted to restrict Fairchild to mesothelioma cases. His Lordship
said that ‘Save only for mesothelioma cases, claimants should henceforth expect little
flexibility from the courts in their approach to causation’: Sienkiewicz, above, n.2, at [187].
None of the other Justices spoke in these very restrictive terms however. For a similar view
of the effect of Sienkiewicz, see P Laleng, ‘Sienkiewicz v Grief (UK) Ltd. and Willmore v
Knowsley Metropolitan Borough Council: A Material Contribution to Uncertainty?’ (2011)
74 Modern Law Review 777, 786-787.
Summers v Tice, 33 Cal 2d 80; 199 P 2d 1 (California Supreme Court, 1948).
Cook v Lewis [1951] SCR 830.
Sienkiewicz [2011] UKSC 10 [105].
Some passages in Ernest Weinrib, The Idea of Private Law (Harvard University Press, 1995)
would tend to suggest that the author held this view of the value of coherence.
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offered for the scope of the law do not explain it, the consequences are that like cases
may be treated differently; claims may be denied or refused without the reasons for
success or failure withstanding scrutiny; and the law may become difficult to predict. If
the law is not accurately conceptualised, there is a danger of errors of analysis being
made in future cases. The current law is unjust (beyond the injustice implicit in its
incoherence) in so far as it conceives of the requirement of causation as a practical tool
for assigning responsibility for an injury, rather than as fundamental to a person’s
entitlement to damages, and so, to a defendant’s liability to pay damages. In this part,
these criticisms of the current law will be developed and traced to the decision in
Fairchild.
A Rationales Outstripping Rules
The reasons given in Fairchild for making an exception to the rule that the
claimant must prove that the defendant’s wrongful conduct caused her damage on the
balance of probability did not justify the ambit of the legal rule supported by their
Lordships in that case. Although some of the reasoning does not go beyond an appeal
to intuitive fairness, three main arguments can be discerned in the judgments for
altering the orthodox requirement that the claimant prove causation on the balance of
probability.17
The first was that insistence upon the orthodox legal burden of proof would
empty of content the defendants’ duty of care in negligence. The duty to take care
would be emptied of content because claimants would never be able to prove that a
particular defendant’s negligence caused its mesothelioma in light of the scientific
uncertainty over the mechanism by which mesothelioma is caused: ‘[i]f liability
depends upon proof that the conduct of the defendant was a necessary condition of the
injury, it cannot effectively exist’.18 Call this the ‘empty duty’ argument.
The second argument was that there was a particular unfairness in the fact that if
only one defendant had breached a duty of care to the claimant that the claimant would
succeed in establishing a claim for damages because that defendant’s wrongful conduct
could be identified as causative but because there were multiple defendants in breach
of duty, the claimant could not recover because he could not point to the causative
defendant. The addition of a wrongful defendant causes one to lose one’s claim for
damages. As Lord Rodger put it: ‘the greater the risk that the men have run at the
hands of successive negligent employers, the smaller the claimants’ chances of
obtaining damages’.19 Call this the ‘multiple wrongdoer’ argument.
The third argument was that a false positive was not as unjust as a false negative.
In other words: holding a negligent, but causally innocent, defendant liable is less
unjust than denying a wrongfully injured claimant a remedy, where a choice must be
made between the two: ‘… such injustice as may be involved in imposing liability on a
duty-breaking employer in these circumstances is heavily outweighed by the injustice
of denying redress to a victim’.20 Call this the ‘relative injustice’ argument.
17
18
19
20
For criticism of Fairchild on the ground that it hardly goes beyond an appeal to very broad
notions of fairness, see Jonathan Morgan, ‘Causation, Politics and Law: Reflections upon the
English – and Scottish – Asbestos Saga’ in R Goldberg (ed), Perspectives on Causation
(Hart, 2011).
Fairchild, [62] per Lord Hoffmann. See also Fairchild at [33] per Lord Bingham and at
[155] per Lord Rodger: ‘The substantive duty of care would be emptied of all practical
content so far as victims are concerned’. A similar consideration had been advanced in
McGhee.
Fairchild, [155]. Cf similarly: Fairchild, at [9] per Lord Bingham.
Fairchild, [33] per Lord Bingham.
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None of these reasons justifies the major limitations placed upon the exception to
the general rule recognised in Fairchild. The limitations were that the exception should
only operate where the claimant has been exposed to sources of risk which are all of
the same kind or which operate in a substantially similar way and that the exception
should only operate where the claimant’s inability to prove causation is a result of
deficiencies in scientific knowledge.
The former requirement is met in mesothelioma cases because the only known
cause of mesothelioma is asbestos: all potential causes of it are therefore the same
(except to the extent that there are different kinds of asbestos dust with different causal
potencies21). Lord Bingham said that: ‘it is one thing to treat an increase in risk as
equivalent to the making of a material contribution where a single noxious agent is
involved, but quite another where any one of a number of noxious agents may equally
probably have caused the damage’.22 Similarly Lord Hutton restricted the decision in
Fairchild to situations ‘where there is only one causative agent’.23 Less exigent was
Lord Rodger’s formulation that the injury be caused ‘by an agency that operated in
substantially the same way’.24
None of the justifications of the decision in Fairchild compels or suggests either
restriction.25 The defendants’ duty of care would equally be without content where
proof is recurrently impossible for reasons independent of the absence of scientific
knowledge and there are multiple different agents or agents which operated in
substantially different ways. If the concern addressed by the ‘empty duty’ argument is
that defendants are not incentivised to adhere to their duties of care – that they are able
to ignore them without fear of sanction – the concern applies wherever there is a
recurrent evidential uncertainty over causation which is reasonably predictable ex ante
by defendants.
It may be correct that a defendant can readily predict severe difficulty in proving
causation against it where the claimant has been or will likely be exposed to similar
risk sources and there is impenetrable scientific uncertainty surrounding the
mechanism by which a risk source operates. In such circumstances it may be rational to
believe that because of the existence of multiple similar risk sources, it will be difficult
to pinpoint the causative source.26 But even if the idea of a similar risk source and
absence of scientific knowledge picks out a relatively sound rule of thumb for one
situation in which a defendant’s duty will be empty of content,27 it cannot provide a
necessary condition for such situations. There are many sources of recurrent and so
predictable uncertainty over causation. For example, lengthy latency periods between
exposure to a toxic agent and disease manifestation give rise to substantial difficulties
of causal attribution because of the diminution of evidence over long periods of time.28
21
22
23
24
25
26
27
28
This fact will not cause a claim to fall foul of the requirement: Barker, at [64] per Lord
Scott.
Fairchild, [22] per Lord Bingham.
Fairchild, [115].
Fairchild, [170]; Lord Hoffmann did not endorse the single agent requirement in Fairchild
but later did in Barker v Corus Ltd. [2006] 2 AC 572, 587. For an obiter approval of Lord
Rodger’s formulation: Novartis Grimsby Ltd. v Cookson [2007] EWCA Civ 1261 at [72].
Similarly: Chris Miller, ‘Causation in personal injury: legal or epidemiological common
sense’, 26 Legal Studies 533, 560-563; Robert Stevens, Torts and Rights (Oxford University
Press, 2007) 51; Allan Beever, Rediscovering the Law of Negligence (Hart, 2007) 475;
Morgan, above, n 17, 61-62. That Fairchild (at least where there is a potential non-wrongful
cause) is limited to cases of scientific uncertainty was confirmed by the Court of Appeal in
Sanderson above n 10.
Another example outside of the mesothelioma context is the mass manufacture of generic
defective drugs.
This is unclear. See below, at pp.253-256.
Cf. the facts of Sindell v Abbott Laboratories 607 P 2d 924 (Cal 1980).
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This has nothing to do with the lack of scientific knowledge. Moreover, in any activity
in which there is a background risk of n% of some harm occurring, D may wrongfully
expose C to a risk of that harm up to n% and if the only evidence is purely statistical,
then it will be impossible to prove that the defendant’s wrongful conduct caused any
claimant’s damage.29
The intuitive unfairness in the idea that the claimant’s legal position becomes
worse the more she is the victim of wrongful conduct by successive persons – i.e. the
less her chances of being able to sue for damages – is also, obviously, independent of
the kinds of causal agents used by those wrongfully subjecting her to risks of injury or
the kind of uncertainty at stake. And, finally, it is obscure how the relative injustices of
the situation change by reference to the types of causal agents used by wrongfully
acting defendants or the type of uncertainty in question.
The difficulty, then, with the substantially similar agent requirement and the
absence of scientific knowledge over the causal mechanism requirement is the jar
created with the underlying reasons adduced to motivate the exception to proof of
causation in the first place. This has only been mildly mitigated by Lord Phillips’
suggestion in Sienkiewicz that Fairchild will apply in an indeterminate wrongdoer
situation involving purely factual uncertainty.30 The substantially similar agent
requirement remains and the requirement of scientific uncertainty continues to apply
beyond the indeterminate wrongdoer situation. The result is a persisting tension
between the underlying principles and their authoritative statement as a legal rule.31
The consequence of this is that claims are rejected for reasons which do not
adequately justify their rejection. Consider the facts of AB v Ministry of Defence.32 The
claimants sought to recover damages for cancer which they alleged had been caused by
their employer’s having negligently exposed them to radiation during their
employment. They could not establish causation on the balance of probability but, at
most, that the defendants had wrongfully materially increased their risk of cancer. The
claim was struck out by the Court of Appeal (whose decision was approved by the
29
30
31
32
See David Kaye, ‘The Limits of the Preponderance of Evidence Standard: Justifiably Naked
Statistics and Multiple Causation’ (1982) American Bar Foundation Research Journal, 487.
It is arguable that cases like Wilsher v Essex Area Health Authority [1988] AC 1074 also
display sufficient ex ante predictable causal uncertainty so as to diminish D’s incentives to
conform to its duty of care. The claimant baby suffered retrolental fibroplasia which caused
him to be blind. One possible cause of his condition was the defendant doctor’s negligent
over-administration of oxygen. However, a number of other possible (non-wrongful)
conditions from which he likely suffered may have caused it. In Wilsher, the fact of multiple
different agents made no difference to the inability to identify the causative agent.
Above, p.246. Lord Phillips’ suggested rationalisation of the single agent rule in Sienkiewicz
at [104] cannot be accepted. His Lordship stated that: ‘The possibility that mesothelioma
may be caused as the result of the cumulative effect of exposure to asbestos dust provides a
justification, even if it was not the reason, for restricting the Fairchild/Barker rule to cases
where the same agent, or an agent acting in the same causative way, has caused the disease,
for this possibility will not exist in respect of rival causes that do not act in the same
causative way.’ From the context in which this suggestion appears, its argument seems to be
that it is the possibility of a cumulative mechanism which makes proof by statistical
evidence impossible. That is partly true (cf below, text at n 48). It remains the case, however,
that this cannot be the only situation in which proof is predictably impossible to establish –
which is what is of normative significance for the ‘empty duty’ argument.
As Jonathan Morgan has observed, this aspect of the reasoning in Fairchild reads as if it
were a ‘legislative attempt to carve out an exceptional category’, in so far as its emphasis
upon the particular is akin to the statutory law’s ability ‘to enunciate precise, isolated legal
rules which apply strictly to the situations intended by Parliament, but have no wider effect’:
Morgan, above n 17, 58, 65.
[2012] UKSC 9.
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Supreme Court) on the ground that there were multiple possible causes of the
claimant’s cancer and so the substantially similar agent requirement under Fairchild
was not satisfied. But since this requirement does not follow from any of the reasoning
in Fairchild, and has no other obvious normative force, it clearly provides insufficient
reason to reject such a claim.
B Analytical Problems
The reasoning of three members of the majority in Barker v Corus led to the law
on proof of causation becoming analytically confused. The seeds of that confusion are
traceable to Fairchild.
In Barker, three of the majority judges held that the damage for which defendants
are held liable under the rule in Fairchild is not mesothelioma but the risk of
mesothelioma.33 The consequence of this was that each defendant was only liable in
proportion to the extent that it had wrongfully exposed the claimant to the risk of
mesothelioma.
This was unnecessary, undesirable, and legally unsustainable.34 It was
unnecessary because it is clear that the only aim sought to be achieved was
proportional liability in situations to which Fairchild applied. It should have been
possible simply to state that liability should be in proportion to the risk that the
defendant caused the damage (as a ‘trade-off’ for the injustice of holding defendants
liable without proof of causation on the balance of probability), rather than holding that
the ‘risk’ was itself damage. It was undesirable because, as Lord Rodger observed, it
created obvious inconsistency with the rejection elsewhere in the law of tort of the
claim that merely subjecting a person to an increase in risk could serve as ‘damage’. It
was legally unsustainable because two of the three claimants in Fairchild and all three
of the claimants in Barker were bringing claims under the Fatal Accidents Act 1976 for
damages in respect of the deaths of their husbands. The Act requires that the death in
respect of which the claimant is suing be ‘caused by any wrongful act, neglect or
default’.35 It is ‘death’ not the risk of death which must be shown under the Act. All of
these claims should have failed if the jurisprudential basis of the Fairchild rule were
that the defendants were liable for causing the risk of mesothelioma.
These problems can hardly be attributed entirely to the House of Lords in
Fairchild. But there are two respects in which Fairchild had encouraged them. The
first is that some of the analysis in the judgments in Fairchild suggests that the
exception to the orthodox burden of proof on causation being created is to be
conceived of as an alteration in the substantive law of causation. Lord Nicholls stated
that a defendant’s causing a material increase in the risk of mesothelioma ‘should be
regarded as a sufficient degree of causal connection’.36 Similarly, Lord Hoffmann
stated that a material increase in risk was being ‘treated…as sufficient in the
circumstances to satisfy the causal requirements for liability’.37 This coheres with Lord
Hoffmann’s argument, expressed extra-judicially, that the substantive causal
requirements for liability depend upon the purpose of the legal rule being interpreted –
from which it follows, given that different rules may have different purposes, that there
33
34
35
36
37
Perhaps the clearest passages to this effect are Barker, [35]-[40] (Lord Hoffmann); [53], [59]
(Lord Scott); [113] (Lord Walker).
One might also add ‘logically incoherent’: if it is impossible to prove causation on the
balance of probability, then one cannot assess the probability that the defendant caused the
damage. But, then, how can one assess the risk (the probability of harm) to which the
defendant exposed the claimant?
Section 1(1).
Fairchild [39], [42].
Fairchild [62].
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is no univocal legal concept of causation – rather the meaning of the word ‘causation’
depends upon interpreting the scope of the particular legal rule at stake.38 If the
substantive requirements of causation can be modified to reflect the underlying
normative considerations of a legal rule (like the ‘empty duty’ argument), then why not
also the concept of damage? In this way, there is a continuity between the normative
analysis of causation in Fairchild and the normative analysis of ‘damage’ in Barker.39
Second, the judgments in Fairchild had placed considerable justificatory weight upon
the idea that the defendants had increased the employees’ risk of mesothelioma. This
was problematic since it is difficult to understand what justificatory role the fact of risk
imposition plays beyond the role already implicit in saying that the defendants have
been negligent – since all negligent conduct involves a risk imposition. So if the idea
of ‘risk’ were to play a non-redundant role in justifying the Fairchild exception, it
could have been thought that its role had to be as forming the damage which the
defendants had caused the claimants. For these two reasons, the problematic analysis in
Barker can fairly be attributed in part to Fairchild.
The idea that the defendants are liable for the risk of mesothelioma (where the
risk is the damage) under the Fairchild exception seems to have been laid to rest by the
recent Supreme Court decision in The Trigger Litigation.40 But the analytical problems
in Fairchild which encouraged the analysis in Barker have not. In the Trigger
Litigation, which concerned whether employers could rely upon Fairchild to establish
that their employee had ‘sustained’ or ‘contracted’ mesothelioma due to the employer’s
negligent exposure (so as to claim under liability insurance policies), Lord Mance
considered that it was ‘entirely natural’ to view Fairchild as imposing a ‘responsibility
for the [employee’s] mesothelioma, based on a ‘weak’ or ‘broad’ view of the ‘causal
requirements’ or ‘causal link’ appropriate in the particular context to ground liability
for the mesothelioma’.41 The idea of different types of causal connection comes from
Hart and Honoré42 (cited by Lord Mance) who distinguished a central concept of
causation (cases of voluntary human interventions or abnormal natural events bringing
about results which would not normally (relative to some viewpoint) occur without
those interventions and without the intervention of a free, deliberate, voluntary action
or abnormal natural event)43 and a weaker concept of causation (providing an
opportunity or means by which another person’s voluntary action causes – in the core
sense – an outcome). Whatever the merits of this pluralist view, these authors were
giving an analysis of the substantive concept or concepts of causation. They were
obviously not considering how to conceptualise a legal exception to the proof of
causation. Nor would they have accepted the incorrect thesis that ‘materially increasing
the risk’ is a species of causal connection which could sit alongside their other types of
causal connection. Materially increasing the risk of a harm is conceptually nothing like
causing it. Rather, materially increasing the risk of harm can either be fictionally
equated with causation of harm for a particular normative purpose or it can serve as a
first step in an evidential inference of causation. Instead of accepting the fictional
route, a better view may be that the law ought to conceive the Fairchild rule as a rule
38
39
40
41
42
43
Lord Hoffmann, ‘Causation’, in Richard Goldberg (ed), Perspectives on Causation (Hart,
2011) 9.
See above, p.250.
[2012] UKSC 14. For a discussion of this aspect of the decision, see Nicholas McBride and
Sandy Steel, ‘The Trigger Litigation’ (2012) 28 Professional Negligence 285.
Trigger [66]. Cf. Lord Clarke, who similarly stated that Fairchild imposes liability upon ‘the
employer who can fairly be said to have caused the disease’ at [83].
HLA Hart and AM Honoré, Causation in the Law (Oxford, 2nd ed, 1985).
For an elegant simplification of this idea of causes as making a difference to normal states of
affairs: Alex Broadbent, ‘The Difference Between Cause and Condition’ (2008)108
Proceedings of the Aristotelian Society 355.
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which reverses the burden of proof on the question of whether the defendant was a butfor or materially contributory cause of its damage when the claimant has proven on the
balance of probability that the defendant materially increased the risk of its damage.
Failure to discharge this burden of proof establishes liability. This liability is then (in
non-mesothelioma cases) made proportionate to reflect the fact that the allocation of
the burden of proof diverges from the orthodox allocation. Designating the rule firmly
as an evidential rather than substantive rule is a truer reflection of the mischief –
evidential uncertainty – to which the rule responds.
C Injustice
The current law is unjust because it holds defendants liable without their being
shown to have caused the claimant damage on the balance of probability without good
reason. I will advance a weaker and a stronger version of this claim. The weaker claim
is that the ‘empty duty’ argument for departing from the orthodox legal burden of
proof on causation is unconvincing in mesothelioma cases. The stronger claim is that
the ‘empty duty’ argument is unconvincing in most imaginable cases.
The ‘empty duty’ argument is basically a deterrence argument. It says that
defendants are insufficiently incentivised to adhere to their duties of care in the tort of
negligence because there will be no sanction for the causative breach of those duties.
This arises as a result of claimants’ recurrent inability to prove causation. In other
words: defendants are insufficiently deterred against breaching their duties of care.44
Here are three reasons why the argument is unconvincing in mesothelioma cases.
First, even if the law of tort provides no sanction for breaches of duties to take care not
to expose persons to asbestos dust, the criminal law often does.45 Secondly, as others
have pointed out, even if it is true that claimants cannot establish on the balance of
probability that a particular defendant has caused their mesothelioma, defendants
continue to have incentives provided by the law of tort to conform to their duties of
care.46 This is because breach of those duties may lead to other asbestos-related
diseases such as asbestosis in respect of which claimants will generally be able to
establish causation on the balance of probability. As asbestosis is worsened by
cumulative exposures, it will generally be possible to establish that a particular
defendant has caused some part of the claimant’s overall condition.47 Thirdly, contrary
to what is often assumed, it is simply not the case that a person can never prove that a
particular defendant’s wrongful conduct has caused her mesothelioma on the balance
of probability. If a person is wrongfully exposed to asbestos for 29 years by D1 and 1
year by D2 and the level of environmental exposure is far smaller than either D1’s or
D2’s exposure, then it should be possible to say on the balance of probability that D1
has contributed to C’s mesothelioma. This is because the uncertainty over the causative
44
45
46
47
Where the argument may differ in part from a standard deterrence argument is in what the
argument considers to be the undesirable consequence which grounds the need to deter
certain kinds of conduct. Normally, deterrence arguments assume that certain kinds of
conduct need to be deterred, where the reason for deterring that conduct is ultimately to
reduce the overall level of harm in the world (or to maximise the level of wealth in the
world). It is possible that the House of Lords in Fairchild thought that part of the reason for
deterring breaches of duties to take care was that it would reduce the overall number of
wrongs (breaches of duties of care) committed in the future, as well as reducing the number
of harms (asbestos-related cancers).
E.g. under Sections 2 and 3 of the Health and Safety at Work Act 1974. Note the recent fine
given to the retailer Marks and Spencer for breach of these provisions: ‘Marks and Spencer
hit with £1m asbestos fine’, The Telegraph, 27 September 2011.
E.g. J Stapleton, ‘Lords a’leaping evidentiary gaps’ (2002) 10 Torts Law Journal 1.
Cf. Holtby v Brigham & Cowan (Hull) Ltd. [2000] 3 All ER 421.
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mechanism only prevents us from ruling out the possible causative impact of a
defendant’s wrongful conduct: as it may be the case that mesothelioma can be caused
by a very small number of asbestos fibres, even a small exposure may have caused a
person’s mesothelioma. However, in D1’s case, it is probable that D1 has contributed
to the mesothelioma regardless of the nature of the causative mechanism. It can be
argued that D1 either contributed by supplying a few fibres sufficient in themselves to
cause the mesothelioma or by supplying fibres which in combination with later fibres
caused the mesothelioma. Whichever the mechanism, it is likely that D1 contributed to
it.48
Now consider five points which tell against the ‘empty duty’ argument quite
generally. First, there is the simple point that it may well be true that beyond the
mesothelioma context there are incentives not to breach duties of care provided by
alternative (criminal) institutions49 and by virtue of the fact that wrongful conduct may
risk more than one type of harm, where at least some of those risked harms will be
provably attributable to defendants. If this is true, then (further) incentives provided by
tort law will be unnecessary. If it is objectionable to hold defendants liable without
proof of causation on the balance of probability, this should not be endorsed if it is
unnecessary.50
Secondly, it must be questioned how much weight one should give to deterrence
arguments when we have such poor evidence as to the concrete effects of tort liability
upon behaviour in particular contexts.51 Even if we assign a speculative empirical
argument some weight, it is hard to accept that that weight is sufficient to outweigh the
principle that the defendant ought only to be made liable if it has been proven on the
48
49
50
51
Cf. J Stapleton, ‘Factual Causation, Mesothelioma and Statistical Validity’ (2012) 128 Law
Quarterly Review 221, 226: ‘Suppose that bladder cancer can only be caused by a particular
agent (amines) and a victim had been, for exactly the same period of time, simultaneously
exposed to only two sources of that agent: occupational amine exposure and amines
contained within cigarette smoke. Suppose further that the volume of the agent from
occupational exposure was considerably more than double that from the smoking exposure.
In such circumstances, it would be possible to infer that it was probable that the dominant
source of the agent, occupational exposure, contributed to the disease: this is because
whatever the mechanism of the cancer, it is probable that the occupational exposure was
involved – for example by being the probable source of the single unit (if that were the
mechanism) or by probably contributing to the threshold (if that were the mechanism) and so
on. (Similar reasoning might be used to help establish that one source of ‘enormous
quantities’ of asbestos relative to other simultaneous sources probably contributed to a
claimant’s mesothelioma.) But it is not a corollary of this proposition that the minor source
of risk probably did not contribute: for example, if the mechanism involved a threshold, that
source would have contributed to it.’
And by the ‘natural’ incentives provided by morality. Cf. Stevens, above n 25, 322: ‘The vast
majority of drivers take care not to run over other people because they consider it morally
wrong to carelessly injure others.’
Polinsky and Shavell argue that it is often the case that sufficient incentives are provided by
market forces and strong regulatory regimes in the context of manufacturers of consumer
products. They go so far as to argue that, in those situations, product manufacturers should
not be subject to any tort liability. It may be true, then, that there are sufficient incentives
provided by alternative institutions in other contexts. See A. Mitchell Polinsky and Steven
Shavell, ‘The Uneasy Case for Product Liability’ (2010) 123 Harvard Law Review 1437.
The empirical evidence available as to the effect of tort liability upon the level of accidents is
‘far from unequivocal’: P Cane, ‘Tort Law as Regulation’ (2002) 31 Common Law World
Review 305, 310. Similarly: Stevens, above n 25, 322-323: ‘The evidence available for the
deterrent impact of the law of torts is thin, and the results are, at best, equivocal’. Perhaps the
most famous empirical study is: D Dewes, D Duff, M Trebilcock, Exploring the Domain of
Accident Law (Oxford University Press, 1996) whose authors often offer agnostic
conclusions in the face of equivocal results (e.g. 205).
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balance of probability to have caused the claimant’s damage. If we think that causation
is normatively very important to grounding the defendant’s liability to pay damages to
the claimant, then commitment to that position requires more than a speculative
empirical argument to justify a departure.52 The point here is not that consequentialist
arguments are never relevant to the question of whether a person ought to bear a
liability – the monist corrective justice position53 – but rather that, without greater
empirical substantiation, they do not outweigh other important normative
considerations.
Compare the following situation involving an empirical uncertainty as to the
effects of liability. Suppose that Doctor negligently fails to diagnose Patient with the
(undisputed) result that Patient suffers a brain injury. If Doctor argued that Patient
should not be compensated by him because there is a chance that the imposition of
negligence liability upon doctors for failures to diagnose would lead doctors generally
to practise defensive medicine (with substantial negative effects upon patients’
welfare), most would not find this argument compelling. The courts obviously do not
accept it.54 But if we find appeal to empirical speculation problematic in rejecting an
otherwise established liability,55 there is some reason to think that appealing to
empirical speculation in establishing an otherwise not established liability is also
problematic.
Thirdly, relying upon the ‘empty duty’ argument to depart from the balance of
probability rule creates a highly unstable exception to the general rule. It is unstable
because there are no available criteria with which to assess with any confidence
whether the exception ought to apply or not in a particular factual situation. This is
because (as we have already said) it is, on the one hand, difficult to tell whether
sufficient incentives to conform to tortious duties already exist outside of the law of
tort and, on the other, it is only possible to conjecture as to whether the imposition of
tort liability in situations of recurrent causal uncertainty will lead to improvements in
the overall number of harms or wrongs since we can only conjecture over what effect
the imposition of liability will have in a situation of recurrent causal uncertainty.
Courts are invited under the ‘empty duty’ argument to assess the impossible question
of whether tort liability will induce incentives beyond those already provided by
morality, regulatory regimes, criminal sanctions, market forces and the fact that
conduct often risks multiple harms some of which will be provably attributable to
defendants.
Fourthly, even if we assumed the empirical validity of the ‘empty duty’ argument,
accepting it creates distributive injustice between classes of claimants (and classes of
52
53
54
55
This objection may seem inconsistent with the last objection. The last objection said that it
may not be necessary to provide incentives to conform to duties under tort law in cases of
recurrent causal uncertainty because of the existence of alternative institutional incentives.
The second objection says that there are not particularly strong empirical credentials to the
‘empty duty’ argument. But if we know little about the empirical effects of tort law, how can
we object that there are or may be alternative incentives – is that not to enter into the
empirical fray without any empirical evidence? Not so. The first objection takes the
incentive argument on its own merits – accepting the various (empirical) assumptions that
defendants are rational, engage in cost-benefit analyses, that judges do not misapply the
standard of care (etc.) and says that even given those assumptions, the argument may not
work. The second objection questions the weight one should give to those empirical
assumptions, given our uncertainty.
The position most often associated with Weinrib, above n 16. Others who exclude
consequentialist considerations are: Beever, above n 25.
Though cf. s 3(1) Compensation Act 2006.
Compare, however, the (inconsistent and problematic) use of such arguments particularly in
cases involving public authorities: Smith v Chief Constable of Sussex Police [2008] UKHL
50.
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defendants).56 Some claimants will receive awards of damages because of the
contingency that they may have been injured by a defendant whose activity is prone to
recurrent causal uncertainty, whilst others will receive nothing because their receiving
compensation does not serve the social goal of deterrence. This injustice is exacerbated
by the fact that, even if we assumed the empirical validity of the ‘empty duty’
argument, it does not necessarily provide an argument for compensating the claimant
rather than another person. It may be the case that allowing private individuals who
have been wrongfully exposed to a risk by the defendants to claim damages against
those defendants for materially increasing their risk of harm in cases where there is
recurrently predictable causal uncertainty reduces the overall level of future harms or
wrongs. But it may be the case that alternative mechanisms could better perform this
function. For example, allowing companies to compete in the market for licences to
sue wrongful risk-increasers may be better at deterring wrongful conduct. The reason
one claimant recovers and the other does not, then, is that it is possibly necessary for
the social goal of deterrence that the former recovers.
A slightly different version of the last point is that, assuming the empirical
validity of the ‘empty duty’ argument, and supposing that we had a non-arbitrary way
of applying it in particular cases, then accepting the argument will result in a
‘checkerboard’ law of torts. It will be akin to Dworkin’s statute which says that only
persons who are born in even years can have abortions in order to reach a compromise
between different views on the morality of abortion.57 Lawyer-economists who support
liability in cases of recurrent causal uncertainty despite the absence of proof of
causation on the balance of probability give examples of situations where liability
would be mandated on the ‘empty duty argument’ which suggest that the law of tort
would become highly ‘dappled’ or checkerboard. Porat, for example, suggests the
introduction of proportionate liability in cases where there is a ‘downward bias’ in the
probability of causation distribution of cases to which a certain activity gives rise.58
That is: in activities where the probability of D’s having caused the claimant’s damage
is frequently below 0.5. He gives the example of an emergency treatment ward where
patients on average have chances of survival of less than 30% such that none can ever
establish causation on the balance of probability in the event of negligence. If we do
think that ‘integrity’ in the law is a distinctive value or a value closely animated by
justice,59 then this kind of unequal treatment of defendants (and claimants) is
problematic.
The third and fourth arguments are to my mind sufficient to dismiss the ‘empty
duty’ argument. The first and second arguments, however, rely upon an as yet
undefended premise.60 Each of these arguments is of the form: ‘given the importance
56
57
58
59
60
Of course it might be objected that tort law is inherently distributively unjust. It allows the
victims of wrongfully caused injury damages against defendants but it does not award
damages to those who suffer serious injury without anyone’s fault. The objection is
misguided. It is defensible that a person who has not been wrongfully injured by a defendant
cannot successfully sue that defendant whilst a person who has been wrongfully caused
injury by that person can. But this restriction becomes difficult to defend if the reason the
defendant is being made liable is to encourage the reduction of overall wrongs or harms.
There is then no reason (beyond a debatable reason of efficiency) to restrict the claim to
those who have wrongfully suffered. For a similar point, see Arthur Ripstein and Benjamin
Zipursky, ‘Corrective Justice in an Age of Mass Torts’ in Gerald Postema (ed), Philosophy
and the Law of Torts, (Cambridge University Press, 2001) 230.
Ronald Dworkin, Law’s Empire (Harvard University Press, 1986) 178.
Ariel Porat, ‘Misalignments in Tort Law’ (2011) 121 Yale Law Journal 82, 108.
For discussion of the value of ‘integrity’, see TRS Allan, ‘Law, Justice, Integrity: The
Paradox of Wicked Laws’ (2009) 29 Oxford Journal of Legal Studies 705.
The arguments made in the text should not be confused with another type of objection to the
‘empty duty’ argument. We can call this the reductio objection. The reductio objection says
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of proof of causation to a person’s entitlement to damages from the defendant, the
force of the empty duty argument is insufficient to outweigh that importance’. But
nothing has yet been said to support the importance of causation to the claimant’s
entitlement to recover from the defendant in respect of its damage. Establishing that
importance will serve to vindicate the first and second arguments by making out a
crucial premise as well as providing a further, independent, point against the ‘empty
duty’ argument.
The importance of causation to establishing that the defendant should compensate
the claimant for its loss may be defended in at least four ways. From a consequentialist
perspective, it may be argued that requiring the claimant to prove that the defendant
caused its injury reduces the efficiency-reducing effect of judicial errors in setting the
standard of care in negligence-based torts and reduces overall administrative costs of
the tort system by reducing the number of claimants who can sue.61 If this account of
the importance of causation were accepted, then the ‘empty duty’ argument (if it had
empirical credentials) would have force. On the consequentialist account, the
normative force of causation is simply a product of whatever good consequences it
brings about (fewer harms or wrongs or economic costs). The ‘empty duty’ argument
says that the usual benefits which insisting upon causation brings are outweighed by
the negative consequence that, in a situation of recurrent causal uncertainty, there is no
incentive to take care provided by the tort system.62 On this account, causation is
simply a practical tool to maximise welfare (or wealth or some good consequence).
Clearly, then, if the first and second arguments are to be successful, they must
rely upon another, more robust, account of the importance of proof of causation.63 One
such account is what we can call the wrong-based account. According to this account,
it is necessary to prove that the defendant caused the claimant’s damage because the
defendant has only wronged the claimant in the event that the defendant has caused the
claimant’s damage. This provides a strong reason not to find defendants liable for
substantial damages absent proof at least on the balance of probability that the
defendant caused the claimant’s damage. To hold otherwise would be to presume that
the defendant is a wrongdoer, when surely the defendant has some entitlement not to
be presumed to have committed a wrong against the claimant. The wrong-based
account has some force so far as the tort of negligence is concerned since many people
think that a constituent element of the legal and moral wrong in negligence is causation
61
62
63
that if we follow the ‘empty duty’ argument to its logical conclusion, there is no need to
insist upon causation in any case. This is because optimal deterrence would be achieved by a
system of liability for pure risk creation. For this objection: D P Nolan, ‘Causation and the
Goals of Tort Law’ in Andrew Robertson and Tang Hang Wu (eds), The Goals of Private
Law (Hart, 2009) 187-190. The problem with this objection is (i) that not all economists
would agree that this is so (see e.g. C Grechenig and A Stremitzer, ‘Der Einwand
rechtmäßigen Alternativverhaltens – Rechtsvergleich, ökonomische Analyse und
Implicationen für die Proportionalhaftung’ (2009) 73 Rabel Journal of Comparative and
International Private Law 336, 358-359); and (ii) it might be argued that tort law should be
reformed better to represent this consequentialist model.
E.g. Marcel Kahan, ‘Causation and the Incentives to Take Care under the Negligence Rule’,
(1989) 18 Journal of Legal Studies 427.
Grechenig and Stremitzer, above n.60, 358-359.
For an early attempt at explaining why causation matters: Judith Jarvis Thomson, ‘Remarks
on Causation and Liability’ (1984) 13 Philosophy & Public Affairs 101. For doubts as to the
importance of causation as a necessary condition of being subject to a liability to compensate
someone: Christopher Schroeder, ‘Causation, Compensation and Moral Responsibility’ and
Jeremy Waldron, ‘Moments of Carelessness and Massive Loss’, both in David Owen, (ed)
Philosophical Foundations of Tort Law (Oxford University Press, 1995).
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of damage.64 This would also provide a reason for insisting upon proof of causation on
the balance of probability in other contexts where the only plausible way in which the
defendant could be said to have wronged the claimant is through having caused the
claimant damage.
But to rely solely upon the wrong-based account would be problematic in two
respects. First, it can plausibly be contended that the defendant legally and morally
wrongs the claimant when it negligently increases the risk of, say, a physical injury to
the claimant by its actions.65 If so, then wrongly finding that the defendant has caused
the claimant physical injury in circumstances where the defendant has been shown to
have negligently risked the claimant physical injury on the balance of probability does
not involve holding that a wholly innocent66 person has committed a legal and moral
wrong, but rather that a person who has breached a legal and moral duty to the
claimant (not negligently to increase C’s risk of physical injury) has committed a
further legal and moral wrong (not negligently to cause C physical injury). This is
perhaps a less serious matter. Secondly, the wrong-based account cannot explain why
we should insist (as surely we ought) that the claimant prove that the defendant caused
her loss in cases of non-causal wrongs (the torts actionable per se).
In addition to the wrong-based account, then, we would also point to the
normative importance of finding that the defendant is responsible for the claimant’s
damage in order to hold the defendant liable to pay compensatory damages in respect
of that damage. We tend to think that it is unjust to make a private individual bear
another’s loss unless the individual is responsible for that loss. The fact of causation is
an essential element of individual responsibility for a loss (outcome responsibility).67
The importance of causal responsibility to the legitimacy of making an individual
liable to bear some loss is evident in our judgments about the permissibility of acting in
self-defence against another person.68 Suppose that Alex’s car is hurtling unstoppably
towards Ben and will kill him unless Ben pushes Carrie, who is trying to kill David
with a gun which, unbeknownst to her but to the knowledge of Ben, is unloaded, into
the path of Alex’s car. It does not seem permissible for Ben to push Carrie in front of
the car, even although Carrie is seriously culpable, because Carrie is not causally
responsible for the threat to Ben. A more humdrum example is where Evan is
negligently shot by Fred having, only seconds before, been negligently risked (but not
caused) the same injury by Greg’s firing a gun. Fred is bankrupt and has no insurance.
It would be a serious injustice to Greg to hold that he should be made to pay for Evan’s
injury when he has not caused it, even although Evan will not be compensated for his
wrongfully inflicted injury. Greg, though he has behaved wrongfully, is simply not
responsible for the injury.
A final reason for thinking that proof of causation is particularly important in
justifying the imposition of a duty to pay substantial damages to compensate for a loss
is what can be called the duty-based account. It is arguable that the only reason for the
state to intervene on behalf of an individual to require another individual to pay
substantial damages is where that person can be said to have a moral duty to the other
64
65
66
67
68
E.g. John Gardner, ‘Obligations and Outcomes in the Law of Torts’ in Peter Cane and John
Gardner (eds), Relating to Responsibility: Essays for Tony Honoré (Hart, 2001).
For this claim about the law: Nicholas McBride, ‘Duties of Care: Do They Really Exist?’
(2004) 24 Oxford Journal of Legal Studies 417.
C.f. Nolan, above n.60, 175; Beever, above n 25, 446.
Nils Jansen, Die Struktur des Haftungsrecht (Tubingen, 2003) 132.
See Jeff McMahan, ‘The Basis of Moral Liability to Defensive Killing’ (2005) 15
Philosophical Issues 386. For the view that causation is important but not determinative, see:
Victor Tadros, The Ends of Harm (Oxford University Press, 2011) 191-196.
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to pay those damages.69 It is not enough to say that imposing liability would make the
claimant better off and not affect the defendant very much because he is well off.
Stronger reason is required. It may be that this stronger reason is only found where a
person can be said to have a moral duty to do what the State is ordering that person to
do. In cases where the defendant has not caused the claimant loss it is hard to identify a
duty which could justify the payment of substantial damages to the claimant. The only
duty which looks as if it could play that role is the secondary duty to compensate the
claimant which would arise out of a breach of the primary obligation not wrongfully to
cause damage to the claimant.70 But without causation of damage, that primary duty is
not breached.
The wrong-based, responsibility-based and duty-based accounts of the
importance of causation together suffice to make out the premise that causation is of
significant normative importance in establishing that the defendant ought to be liable to
pay substantial damages to the claimant. Given this importance, it is legitimate to insist
that claimants at least prove that the defendant probably caused their damage. And
given this importance, it is unacceptable to depart from this rule on the basis of a
speculative empirical argument in circumstances where it may be unnecessary to do
so.71
This section has argued that the current law is unjust because the ‘empty duty’
argument relied upon by the House of Lords in Fairchild does not provide good reason
to depart from the rule that the claimant prove causation on the balance of probability
in mesothelioma cases and in others. This naturally raises the question whether the law
can ultimately be justified upon some other ground even if the ‘empty duty’ argument
is unsuccessful. In the next part, I suggest that there is a justification for an exception
to proof of causation on the balance of probability in the indeterminate wrongdoer
situation for reasons akin to the second and third arguments made by the House of
Lords in Fairchild.72 This justification is limited, however, to indeterminate wrongdoer
cases and could not expand beyond them.
Let us briefly consider two significant alternative justifications for the current
law’s position that claimants ought to obtain proportional damages against defendants
in circumstances where they have not shown that it is even probable that the
defendant’s wrongful conduct caused their damage (and where it is not shown that the
claimant has suffered their loss as a result of wrongful conduct).73 The first is that
increasing the risk of harm is itself to cause harm. If this were true, proving that the
defendant wrongfully increased the risk of harm would itself be to have proven that it
has caused damage. But, as others have pointed out, it is highly problematic to say that
increasing the risk of harm is itself harming.74 It is hard to accept that a person who is
exposed to a risk which does not materialise and who is never aware of having been
placed at risk has been harmed. If they have, then every time a person is exposed to
69
70
71
72
73
74
It is only arguable as there are obvious potential counter-examples. It might be said that
liability in unjust enrichment does not enforce a moral duty to repay the enrichment, for
example. (See, e.g., Stephen Smith, ‘Duties, Liabilities and Damages’ (2012) 125 Harvard
Law Review, 1727. Looking more generally to state interference, it is difficult to justify
punishment as enforcing a moral duty. For an attempt to do so, see Tadros, above n 68.
For a plausible explanation of the sense in which secondary obligations derive from breach
of primary obligations, see John Gardner, ‘What is Tort Law For? Part 1: The Place of
Corrective Justice’ (2011) 30 Law and Philosophy 1.
See the first two objections, above, p.253-254.
See above, p.247-248.
Other potential justifications are discussed in Chapters 2 and 3 of Sandy Steel, Proof of
Causation in Tort Law (Cambridge University Press, forthcoming).
E.g. Stephen Perry, ‘Risk, Harm and Responsibility’ in David Owen (ed), Philosophical
Foundations of Tort Law (Oxford University Press, 1995) 334-336.
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another’s negligent driving they have been harmed. Moreover, even if we were willing
to accept that risk imposition is itself harmful, it is doubtful that the kind of harm
suffered by the claimant would merit a claim for substantial damages.75
The second argument is offered by Professors Porat and Stein. They suggest that
in some cases ‘accuracy in fact-finding is undermined by circumstances for which no
person can be blamed’ but that ‘in other cases…the existing uncertainty and the
consequent inability of the court to determine the facts accurately result from a
person’s wrongful conduct’.76 In such cases, they say that the defendant has inflicted
‘evidential damage’ upon the claimant. Evidential damage is inflicted whenever the
defendant ‘impair[s] the plaintiff’s ability or reduce[s] his chances to establish the facts
necessary for prevailing in a … lawsuit’.77 It is then argued that wrongful infliction of
evidential damage should give rise to damages in proportion to the probability that the
evidence would have sustained the legal claim.
It seems clear that the authors would hold that the defendants in Barker and
Sienkiewicz inflicted evidential damage upon the claimant. They hold, for example,
that in cases like Hotson v East Berkshire Health Authority,78 where it was unclear
whether a doctor’s negligent failure to diagnose the claimant timeously had caused his
hip injury, that the doctor’s negligence inflicted evidential damage. The basic problem
with these claims is that it is entirely unclear what distinguishes the defendant’s
conduct in cases like Hotson, Barker and Sienkiewicz from any other cases of negligent
conduct. In other words: if the defendant has inflicted evidential damage in Hotson and
Sienkiewicz, then there seem to be no cases in which a negligent defendant will not be
said to have inflicted evidential damage. Porat and Stein could respond that, in fact, in
every case where a defendant has been negligent, evidential damage has been inflicted
in the sense that: had the defendant not been negligent, the claimant would not be
asking the question of whether that negligence caused its damage. In that sense, the
defendant is a but-for cause of the claimant’s uncertainty over causation. This would
conflate two propositions, however: causation of uncertainty and causing there to be
less evidence of something. The defendant doctor in Hotson was a but-for cause of the
claimant’s being uncertain over whether his negligence caused the hip injury. But it
does not follow that the defendant deprived the claimant of the evidence necessary to
substantiate that claim. Only the latter could realistically justify some alteration in the
general proof rules and in most cases not involving destruction or failures to maintain
information-storing items, this is not the case.
The conclusion to be drawn from this section, then, is that the House of Lords in
Fairchild justified an exception to proof of causation on the balance of probability with
an argument which was hardly tenable on the facts of the case and which is deeply
problematic as a matter of principle. Although there may be other potential
justifications not discussed here for departing from proof of causation on the balance of
probability, the discussion here suggests that it is unlikely that the scope of the current
law can be justified on alternative grounds.
75
76
77
78
See, at length, Sandy Steel, ‘Rationalising Loss of a Chance in Tort’, in E Chamberlain, J.
Neyers, S. Pitel (eds) Challenging Orthodoxy in Tort Law (Hart, forthcoming 2013).
Ariel Porat and Alex Stein, Tort Liability Under Uncertainty (Oxford University Press,
2001) 160.
Ibid 161.
[1987] 1 AC 750.
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III A PATH NOT TAKEN
This part argues that the decision itself in Fairchild was correct. However, it was
possible to reach that decision without reliance upon the problematic ‘empty duty’
argument. The result could have been justified on a ground of fairness. The
justification is that we ought not to allow a wrongdoer, whose liability to the claimant
is established, to benefit by relying upon another person’s wrongful conduct. In
Fairchild, one of the defendants had wrongfully injured the claimant. Rejecting the
claim would be allowing that defendant to avoid liability due to the presence of another
person behaving wrongfully. This is similar to the second argument relied upon by the
House of Lords that the claimant ought not to be prejudiced by the presence of an
additional wrongful actor. If we accepted this as a condition for departing from the
orthodox burden of proof on causation, only Fairchild would be correct. In Barker and
Sienkiewicz, the court did not know that it would be allowing a defendant, who had
causally wronged the claimant, to benefit from another’s wrongful conduct were it not
to award damages since the claimant’s injury may have been caused by a non-wrongful
cause. The first section below introduces the argument with an analogy. The second
section below defends it against objections.
A An Analogy
The justification for the principle being proposed is that it is problematic to allow
the defendant (unidentified though he may be) who has wrongfully caused the
claimant’s damage in Fairchild to rely upon the fact another defendant has behaved
wrongfully to avoid liability.79
We find this idea implicit in other parts of the law on causation in tort. Consider
Baker v Willoughby.80 In that case the defendant negligently ran the claimant down on
September 12 1964, permanently injuring the claimant’s left leg. The courts thought
that £1,600 would fairly compensate him for the loss of effective use of his leg for the
rest of his life. On November 29 1967, that same left leg was shot by armed robbers
and had to be amputated. The issue in Baker was whether what happened in 1967
should have an effect on the defendant’s liability to the claimant. The defendant argued
that it should on the ground that the claimant would have lost the effective use of his
leg after November 29 1967 anyway and so compensation should only be due for the
period between September 12 1964 and November 29 1967. The claimant argued that
this would be seriously unjust since he would not be compensated for the loss of the
use of his leg from November 29 1967 onwards. If the claimant sued the robbers he
would only have obtained minimal damages since his leg was already effectively
useless by the time of the robbery. The House of Lords held that defendant’s liability
was not to be reduced by the subsequent independent wrongful conduct of another
person.
Had, however, the claimant in Baker been totally incapacitated on November 29
1967 by a dormant spinal disease caused by no one’s wrongdoing, the defendant’s
liability would have been reduced.81 The defendant is allowed to point to a subsequent
independent non-wrongful event, but not to another’s wrongdoing to reduce his or her
liability to the claimant. In other words, there is a difference between a case where all
79
80
81
For related suggestions: Mark Geistfeld, ‘The Doctrinal Unity of Alternative Liability and
Market Share Liability’ (2006) 155 University of Pennsylvania Law Review 447 (who
endorses a similar type of argument); Jonathan Morgan, ‘Lost Causes in the House of Lords’
(2003) 66 Modern Law Review 277. C.f. Stevens, above n 49, 147 (who rejects it).
[1970] AC 467.
Jobling v Associated Dairies Ltd. [1982] AC 794.
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of the causes of the claimant’s loss are wrongful and a case where one of the causes is
non-wrongful.
Now consider a modified Baker v Willoughby. D1 negligently shoots X in the
head. Independently of D1, D2 negligently shoots X in the head at the same time. Each
shot is independently sufficient to cause X’s death. In this case, it seems highly likely
that English law would hold both D1 and D2 liable in solidum in respect of X’s death.
This result would follow even although neither D1 nor D2’s negligence could be said
to be a but-for cause of X’s loss.82 That is to say: although but-for causation is shown
against neither defendant, X’s estate would succeed in full against both in respect of
the entirety of its losses. And everyone seems to agree that this is the right result
despite the fact that neither defendant has made the claimant any worse off.83 Call this
case Overdetermined Death, because X’s death was causally overdetermined.
In Fairchild, one of the defendants is seeking to rely upon the uncertainty created
by another person’s wrongful conduct so as to reduce his liability to the claimant. Just
as in Overdetermined Death, neither defendant is shown to have been a but-for cause
of the claimant’s damage. The result of rejecting liability is that the claimant ‘falls
between two stools’: the causative wrongdoer and the person who has negligently
risked damage to the claimant. Although the defendant who is seeking to do this is
unidentified, it still seems objectionable to allow the defendant, whoever he or she may
be, to take advantage of the uncertainty created by the other person’s wrongful
conduct.
The natural objection to this is that even if it is objectionable to allow a
wrongdoer to reduce partially or entirely their liability to the claimant by relying upon
another person’s wrongful conduct, this does not justify imposing liability upon the
wrongdoer who has not caused any damage. After all, the robbers in Baker v
Willoughby would not have been liable for the loss which had already occurred in that
case even although they would have been, in a sense, relying upon the earlier
wrongdoing of the defendant.84
The response is that, in Fairchild, the court is not knowingly violating the
defendant’s entitlement to be free of liability for damage which it has not caused (as it
would be if it held the robbers liable in Baker). Rather, it is risking the possibility that
the defendant has not caused the damage in circumstances where the defendant may
have wrongfully caused the damage in order to preclude reliance upon another’s
82
83
84
Although each defendant is a NESS cause of the death (a necessary element of a set of
conditions sufficient for the death), it is still the case that damages ought generally not to be
awarded in cases where the defendant has not made the defendant worse off. So even if C
shows that D is a NESS cause of C’s loss, it remains for C to show that C is worse off as a
result of D’s wrongful conduct. Separating this question from the causal question, see Jane
Stapleton, ‘Cause-in-Fact and The Scope of Liability for Consequences’ (2003) 119 Law
Quarterly Review 388, 412-417.
It will be objected that the claimant has a right to be free from the negligent infliction of
injury and that therefore the appropriate counterfactual world in assessing whether each
defendant has made the claimant ‘worse off’ is one in which the claimant does not suffer
physical injury through the negligent wrongdoing of anyone . But the claimant has no such
right as against each defendant. The defendant owes the claimant a duty not negligently to
cause the claimant physical injury, not a duty to protect the claimant from the wrongdoing of
third parties. C.f. Arthur Ripstein, ‘As If It Had Never Happened’ (2007) 48 William and
Mary Law Review 1957.
It could be argued that the robbers would have been liable on the basis that they destroyed
the claimant’s ability to sue the defendant for losses which would have happened anyway
and that this was not too remote a loss because the defendants had behaved intentionally. But
the decision in Baker precludes this argument. It is in any event seriously problematic: see
Nicholas McBride and Sandy Steel, ‘Suing for the Loss of the Right to Sue: Why Wright is
Wrong’ (2012) 26 Professional Negligence 27.
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wrongdoing. There is a difference between knowingly using the defendant as a means
to compensate another person for a wrong for which it is not responsible and risking
that possibility both in order to preclude reliance upon wrongdoing and where there is
still the possibility of correcting the injustice inflicted upon the claimant by holding the
party responsible for the loss liable (as there is not with the robbers in Baker).
There is, however, a significant normative difference between cases like
Fairchild and cases like Overdetermined Death in virtue of the fact that one of the
defendants has not been shown even to have contributed to the claimant’s damage, but
only wrongfully to have risked that damage. To recognise this difference between the
cases, there is a plausible argument for holding (as the current law does in nonmesothelioma cases) that the defendant’s liability should only be proportionate to the
risk to which it has exposed the claimant. This is a reflection of the fact that some
inroad has been made upon the defendant’s claim not to be subject to a liability absent
proof of causation on the balance of probability.
Before turning to some further objections to this argument, we may note the
virtues which an emphasis upon the normative consideration of precluding reliance
upon wrongdoing would bring to the current law. First, it avoids the ‘instability’
objection to the ‘empty duty’ argument. Courts would not be asked to assess an
impossible empirical question concerning the incentives provided by the imposition of
liability but may rather rest upon the wholly normative consideration of precluding
reliance upon another’s wrong to the detriment of the claimant. Secondly, it avoids the
‘distributive injustice’ objection. It may seem odd that a claimant who cannot prove
causation against a negligent defendant but whose damage may have been caused by a
non-wrongful cause does not succeed under the present argument but a claimant who
has been the victim of a wrong but who cannot identify the causative wrongdoer does
succeed. But, as we noted above, the law already accepts a distinction between cases
where a person is seeking to rely upon the wrongdoing of another and cases where a
person is seeking to point to a non-wrongful event. Moreover, it is possible to justify
differential treatment by tort law of these persons precisely because the second person
has been shown to have suffered a tortious wrong.85 Thirdly, it would bring the law
into line with the position taken by most American States, Canada, Germany and
France – all of which allow a special limited exception to proof of causation on the
balance of probability in indeterminate wrongdoer cases.86
B Objections
A first objection is made by Professor Stevens. The result of the rule being
proposed is that ‘an employer who employed the claimant for one day during a 40-year
career in working with asbestos with multiple employers would be held liable in full
for the injury, although the overwhelming probability must be that he was not its
cause’.87 A first point is that, if the defendant is able to prove on the balance of
probability it was not in fact a cause, it should not be liable. Fairchild should only
apply where one cannot ascertain on the balance of probability who caused the
85
86
87
‘[T]here seems to be a significant leap between making whole a plaintiff who has suffered a
tortious injury and allowing recovery to one whose injury might not otherwise fall within the
scope of tort law’: Ernest Weinrib, ‘A Step Forward in Factual Causation’ (1975) 38 Modern
Law Review 518, 525.
For the United States, France, and Germany, see Sandy Steel, ‘Sienkiewicz v Greif and
Exceptional Doctrines of Natural Causation’ (2011) 2 Journal of European Tort Law 294.
The Canadian position is now reflected by Clements v Clements 2012 SCC 32 which accepts
a limitation to indeterminate wrongdoer cases.
Stevens, above n 49, 147.
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damage. A second point is that, under the proposed rule, liability would be in
proportion to the risk so this intuitively unfair result would be substantially mitigated.
A second objection is that the argument involves illegitimately looking beyond
the bipolar relationship of the defendant to the claimant and so violates the principle of
‘correlativity’ which states that the only normative considerations relevant to
adjudicating between two individuals are considerations which link the two parties
together in the one ‘normative relationship’.88 On this objection, the fact that the
defendant is relying upon another person’s wrong is not sufficiently related to the
relationship of the defendant to the claimant. A first response is that the principle of
correlativity must have limits. If a third party will kill one hundred innocent people
unless a judge wrongly holds a defendant liable in damages, the judge should hold the
defendant liable in damages. There are disputes as to where these limits lie. The
argument made here suggests another limit which is already recognised in other parts
of the law on causation in tort. A second response is that the ‘correlativity’ principle
will lead to very strange results in much more ordinary cases. Consider the following
case. D1 and D2 independently wrongfully cause a minor explosion near where C1 and
C2’s cars are parked. Each explosion destroyed one car but it is impossible to say
which explosion caused which car to be destroyed. It seems extremely unjust to say
that C1 should not be able to sue either D1 or D2. Both defendants have wrongfully
caused damage to one of the claimants and may have caused that damage to the
particular claimant, who is certainly the victim of a wrong at the hands of one of the
defendants.89
A third objection to the argument is that, just like the ‘empty duty’ argument’, it
works an injustice against the causally innocent defendant in Fairchild. Whereas the
‘empty duty’ argument uses the causally innocent defendant as a means to pursue the
socially beneficial goal of deterring future wrongs or harms (and so commits an
injustice), the ‘reliance upon another’s wrong’ argument uses the causally innocent
defendant as a means to compensate the claimant in respect of a wrong for which the
defendant is not responsible. Either way, the defendant is being held responsible for
loss which it did not cause – what does it matter (to the defendant’s responsibility) that
that claimant’s loss is a result of another person’s wrongdoing?
There is certainly force in this objection. But it has its own problems. It
mischaracterises the injustice inflicted in cases like Fairchild. The injustice inflicted by
the court in a Fairchild case is not constituted by the fact that one of the defendants is
held liable for a harm for which it is not responsible. This injustice occurs whenever a
person is held liable for a harm which it did not cause. But so long as we are confident
on the balance of probability that the defendant caused the harm, then (even if the
defendant did not cause the harm in reality) the injustice is acceptable.90 The
88
89
90
On ‘correlativity’, see generally Ernest Weinrib, ‘Correlativity, Personality, and the
Emerging Consensus on Corrective Justice’ (2001) 2 Theoretical Inquiries in Law 107. For
reliance upon ‘correlativity’ in the context of an argument against liability in the
indeterminate wrongdoer situation, see Nolan, above n 60, 174-176.
The only way around this case for those committed to ‘correlativity’ seems to be along the
following lines. In the example of two cars, each D knows that it has causally wronged
someone and therefore that it ought to compensate someone. Given this knowledge, each D
cannot simply do nothing. Rather, D’s secondary obligation arising out of the commission of
a wrong is to make an agreement with the other defendant whereby they jointly authorise
each other to compensate the claimants in respect of their wrong. If the defendants fail to
conform to this secondary obligation, perhaps the courts can hold them liable for that. I
develop this as a potential solution to mass tort cases in which D is known to have
wrongfully caused damage in Steel, above n 73, Chapter 2.
For a helpful discussion of the morality of standards of proof, see Ronald Dworkin, A Matter
of Principle (Harvard University Press, 1985) Chapter 3.
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(potentially unacceptable) injustice is rather that the court is wrongfully imposing too
great a risk of an incorrect verdict against the defendant. If the defendant is entitled
minimally to proof on the balance of probability of causation, then by insisting upon
something less, the court is taking too great a risk of a false positive on the causal
question. The pertinent question, then, is really: why should the presence of another
wrongful actor affect the defendant’s entitlement that a case be proved against it on the
balance of probability?
The response is that whilst it may be impermissible to knowingly risk a false
positive where the risk is greater than 50% (imagine the wrong committed by holding
D liable where it is shown on the balance of probability that D did not cause the
damage) it is not so obvious that taking the risk of a false positive against the
defendant is impermissible where the risk of a false positive is unknown and
unknowable. In Fairchild cases it is impossible to assess the probability that the
defendant caused the damage. In cases where it is impossible to decide the matter
according to the substantive law according to the governing standard of proof (a
burden of proof situation), it becomes more plausible to say that other normative
considerations can outweigh the defendant’s general entitlement not to be liable absent
proof of causation.91 One such consideration is the fact that the causative defendant is
relying upon another’s wrong to evade liability.92
IV CONCLUSION
This article has been highly critical of the decision in Fairchild. It created
explanatory and analytical incoherence in the law. It led to unjust developments in the
law by its failure to restrict the exceptional rule being created to the normatively
singular indeterminate wrongdoer situation where the causative defendant is relying
upon another’s wrongful conduct to evade liability.
91
92
C.f. Ripstein and Zipursky, above n 56, 242.
Another, peculiar to Fairchild itself, is that it was extremely probable that an injustice would
be committed against the claimant in Fairchild but only possible that an injustice would be
committed against both defendants. If the mechanism of mesothelioma is cumulative, both
defendants may have played a role in its occurrence.