What’s the Chance? Causation Issues in Tort
Law
Prof. Michael D. Green, Wake Forest Law School
Profs. John Church and Bill Corbett, LSU Law Center
I. THE BASIC STANDARDS
A. But-for Causation
The basic standard of causation in tort law is but-for causation. The usual
formulation or statement of that standard, with the burden of persuasion is, “It is
more probable than not that but for the breach the harm would not have
occurred.
1. National: THE RESTATEMENT (THIRD) OF TORTS: LIABILITY FOR PHYSICAL
AND EMOTIONAL HARM § 26 states the standard as follows:
Tortious conduct must be a factual cause of harm for liability to be
imposed. Conduct is a factual cause of harm when the harm would not
have occurred absent the conduct. Tortious conduct may also be a
factual cause of harm under § 27.
2. Louisiana courts often refer to the standard of causation as “substantial
factor,” but define this as but-for causation:
For example, the Louisiana Supreme Court stated as follows in Rando v. Anco
Insulations, Inc., 16 So. 3d 1065, 1089 (La. 2009):
In Dixie Drive It Yourself System v. American Beverage Co.,
242 La. 471, 137 So. 2d 298 (1962), we stated that “conduct is a
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cause-in-fact of harm to another if it was a substantial factor in
bringing about that harm.” Id. at 302. Elaborating on that
pronouncement of law, we stated negligent conduct is a substantial
factor if the harm would not have occurred without the conduct, i.e.,
but for defendant's conduct, plaintiff would not have sustained injury.
Thereby, we equated the two concepts of substantial factor and
necessary antecedent. Malone, Ruminations on Dixie Drive It Yourself
Versus American Beverage Company, 30 La.L.Rev. 363, 373 (1970).
“Cause-in-fact is usually a ‘but for’ inquiry which tests whether the injury would
not have occurred but for the defendant's substandard conduct. . . . The cause-infact issue is usually a jury question unless reasonable minds could not differ.” Cay
v. State, 631 So. 2d 393, 395-96 (La. 1994). A good way to understand this
inquiry is imagine rewinding a DVD to the time of the defendant’s negligent act,
removing that act from the DVD and then replaying it. If the plaintiff does not
suffer the harm in the hypothetical replaying, the negligence was a cause in fact-ofthe harm. David W. Robertson, The Common Sense of Cause in Fact, 75 Tex. L.
Rev. 1765, 1770-71 (1997).
B. Other, Lower Standards of Causation
1. National: THE RESTATEMENT (THIRD) OF TORTS: LIABILITY FOR PHYSICAL
AND EMOTIONAL HARM § 27:
If multiple acts occur, each of which under § 26 alone would have
been a factual cause of the physical harm at the same time in the
absence of the other act(s), each act is regarded as a factual cause of
the harm.
a. Multiple sufficient causes generally. This Section applies whenever
there are two or more competing causes, each of which is sufficient
without the other to cause the harm and each of which is in operation
at the time the plaintiff's harm occurs. When an actor's tortious
conduct is such a cause, it nevertheless would not be a factual cause if
factual causes were limited to the definition in § 26: even without that
tortious conduct, the harm would still have occurred because of the
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competing cause. Nevertheless, courts have long imposed liability
when a tortfeasor's conduct, while not necessary for the outcome,
would have been a factual cause if the other competing cause had not
been operating.
2. Louisiana: Louisiana courts sometimes seem to be applying a causation
standard lower than but-for:
This case appears to be a close one on the issue of cause-in-fact. It is
likely that this accident might have occurred had Benoit, who already
owned a weapon, never been commissioned. Thus, it is impossible to
say with any degree of certainty, “but for” the sheriff's conduct, this
accident would not have happened. Nonetheless, inasmuch as the
sheriff's actions can be said to have appreciably enhanced the chance
of the accident occurring, they are a cause-in-fact of the accident.
Roberts v. Benoit, 605 So. 2d 1032, 1052 (La. 1992) (on reh’g). Note, by analogy
to causation in toxic torts, if the sheriff’s conduct slightly more than doubled the
risk of harm, it would satisfy the preponderance standard of proof. RESTATEMENT
(THIRD) OF TORTS: LIABILITY FOR PHYSICAL AND EMOTIONAL HARM § 28 cmt.
C(4).
II. SHIFTING BURDEN: BURDEN SHIFTS TO DEFENDANTS TO
DISPROVE CAUSATION
A. National: started with Summers v. Tice, 199 P. 2d 1 (Calif. 1948) (two hunters
shooting in direction of third hunter and third was hit in eye and lip by shotgun
pellets).
THE RESTATEMENT (THIRD) OF TORTS: LIABILITY FOR PHYSICAL AND EMOTIONAL
HARM § 28:
(a) Subject to Subsection (b), the plaintiff has the burden to prove that
the defendant's tortious conduct was a factual cause of the plaintiff's
harm.
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(b) When the plaintiff sues all of multiple actors and proves that each
engaged in tortious conduct that exposed the plaintiff to a risk of harm
and that the tortious conduct of one or more of them caused the
plaintiff's harm but the plaintiff cannot reasonably be expected to
prove which actor or actors caused the harm, the burden of proof,
including both production and persuasion, on factual causation is
shifted to the defendants.
B. Louisiana applies a shifting burden on causation to legal malpractice cases:
Jenkins v. St. Paul Fire & Marine Ins. Co., 422 So. 2d 1109 (La. 1982).
III. LOST CHANCE
A. National:
1. Acceptance: Started with Herskovitz v. Group Health Coop. of Puget
Sound, 664 P.2d 474 (Wash. 1983) and Prof. Joseph H. King, Jr.’s article,
Causation, Valuation, and Chance in Personal Injury Torts Involving Preexisting
Conditions and Future Consequences, 90 YALE L. J. 1353 (1981).
RESTATEMENT (THIRD) OF TORTS: LIABILITY FOR PHYSICAL AND EMOTIONAL HARM
§ 26 Comment n:
n. Lost opportunity or lost chance as harm. A number of courts have
recognized a lost opportunity (or lost chance) for cure of a medical
condition as a legally cognizable harm. This new characterization of
harm permits recovery when adherence to traditional categories of
legally cognizable harm and rules of proof of causation would not.
Under the preponderance-of-the-evidence standard, plaintiffs fail in
their burden of proving factual causation if they do not introduce
evidence that proper care more likely than not would have cured or
otherwise improved their medical condition. Thus, courts traditionally
have required that a plaintiff show that the probability of a better
outcome was in excess of 50 percent. Plaintiffs who do provide such
proof, of course, recover the entirety of their damages.
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Concomitant with this reconceptualization of the harm for a plaintiff
unable to show a probability in excess of 50 percent is an adjustment
of the damages to which the plaintiff is entitled. Rather than full
damages for the adverse outcome, the plaintiff is only compensated
for the lost opportunity. The lost opportunity may be thought of as the
adverse outcome discounted by the difference between the ex ante
probability of the outcome in light of the defendant's negligence and
the probability of the outcome absent the defendant's negligence.
These decisions are a response to inadequate (and unavailable)
information about what would have been the course of a specific
patient's medical condition if negligence, typically in failing to
diagnose, refer, or otherwise provide proper treatment, had not
occurred. Lost chance thus serves to ameliorate what would otherwise
be insurmountable problems of proof, i.e., proving what would have
happened to the plaintiff or plaintiff's decedent if proper medical care
had been provided. Among courts that are inclined to modify the law
in this area in response to the difficulties of proof, recognizing lost
opportunity as harm is preferable to employing a diluted substantialfactor or other factual-causation test, thereby leaving recovery to the
unconstrained inclination of any given jury and providing some
fortunate plaintiffs with a full measure of damages for their physical
harm while denying any recovery to others. For courts adopting lost
opportunity, however, Restatement Second, Torts,§ 323 does not
supply support for such a reform, for the reasons explained in the
Reporters' Note to this Comment.
The lost-opportunity development has been halting, as courts have
sought to find appropriate limits for this reconceptualization of legally
cognizable harm. Without limits, this reform is of potentially
enormous scope, implicating a large swath of tortious conduct in
which there is uncertainty about factual cause, including failures to
warn, to provide rescue or safety equipment, and otherwise to take
precautions to protect a person from a risk of harm that exists. To
date, the courts that have accepted lost opportunity as cognizable
harm have almost universally limited its recognition to medicalPage 5 of 10
malpractice cases. Three features of that context are significant: (1) a
contractual relationship exists between patient and physician (or
physician's employer), in which the raison d'être of the contract is that
the physician will take every reasonable measure to obtain an optimal
outcome for the patient; (2) reasonably good empirical evidence is
often available about the general statistical probability of the lost
opportunity; and (3) frequently the consequences of the physician's
negligence will deprive the patient of a less-than-50-percent chance
for recovery. Whether there are appropriate areas beyond the medicalmalpractice area to which lost opportunity might appropriately be
extended is a matter that the Institute leaves to future development.
Recognizing a lost opportunity for cure is not strictly a matter of
factual causation; rather, it reconceptualizes the harm. Once the harm
is reconceptualized as the lost opportunity, the factual-cause inquiry
changes. See Comment f. Both because the lost-opportunity doctrine
is one involving the definition of legally cognizable harm and because
it has been confined to medical malpractice, a specialized area of
negligence liability outside the scope of this Restatement, the Institute
takes no position on this matter, leaving it for future development and
future Restatements.
2. Rejection: Reasons to reject lost chance theory were articulated by the
Texas Supreme Court in Kramer v. Lewisville Memorial Hosp., 858 S.W.2d 397,
405-06 (Tex. 1993):
Unless courts are going to compensate patients who “beat the odds”
and make full recovery, the lost chance cannot be proven unless and
until the ultimate harm occurs. . . . Hence, legal responsibility under
the loss of chance doctrine is in reality assigned based on the mere
possibility that a tortfeasor's negligence was a cause of the ultimate
harm. . . . That damages for loss of chance may be reduced to some
degree is ultimately beside the point.
****
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Furthermore, assuming we adopt the loss of chance doctrine in
the context of this medical malpractice action, it is doubtful that there
is any principled way we could prevent its application to similar
actions involving other professions. If, for example, a disgruntled or
unsuccessful litigant loses a case that he or she had a less than 50
percent chance of winning, but is able to adduce expert testimony that
his or her lawyer negligently reduced this chance by some degree, the
litigant would be able to pursue a cause of action for malpractice
under the loss of chance doctrine. . . . We see nothing unique about
the healing arts which should make its practitioners more responsible
for possible but not probable consequences than any other negligent
actor.
B. Louisiana:
1. Recognized in Hastings v. Baton Rouge Gen. Hosp., 498 So. 2d 713 (La.
1986).
2. Method of valuation: fact finder determines value of lost chance without
multiplication of percentage chance by wrongful death damages. Smith v. State,
Dep’t of Health & Hosps., 676 So. 2d 543 (La. 1996). The Court in Smith rejected
the idea that it was changing the standard of causation:
Allowing recovery for the loss of a chance of survival is not, as
the court of appeal suggested, a change or a relaxation of the usual
burden of proof by a preponderance of the evidence. Rather, allowing
such recovery is a recognition of the loss of a chance of survival as a
distinct compensable injury caused by the defendant's negligence, to
be distinguished from the loss of life in wrongful death cases, and
there is no variance from the usual burden in proving that distinct loss.
Smith, 676 So. 2d at 547.
The Court’s explanation would mean that a plaintiff who lost a chance of survival,
but ultimately survived could recover for the lost chance. Louisiana has such a
case: Claudet v. Weyrich, 662 So. 2d 131 (La. App. 4th Cir. 1995).
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3. Lost chance of a better outcome: Hargroder v. Unkel, 888 So. 2d 953
(La. App. 2d Cir. 2004) (lost chance of better recovery from a stroke), writ denied,
893 So.2d 874 (La. 2005); Graham v. Willis-Knighton Med. Ctr., 699 So. 2d 365
(La. Cir. 1997) (lost chance of saving a limb); Bianchi v. Kufoy, 53 So. 3d 530 (La.
App. 3d. Cir. 2010) (post-surgical care of patient took away or diminished patient's
chance for a better recovery from his surgery).
IV. CAUSATION IN INTERSECTING THEORIES OF RECOVERY
The issue is illustrated by Libersat v. J&K Trucking, Inc., 772 So. 2d 173 (La.
App. 3d Cir. 2000), writ denied, 789 So. 2d 598 (La. 2001).
Plaintiff asserted that truck driver was negligent in executing turn and hitting
plaintiff. Evidence established that driver was not negligent. Plaintiff argued for
jury to be instructed on negligent hiring because trucking company had hired
driver with bad driving record. The court stated as follows:
After a review of the record, this Court finds that the trial court's
instructions regarding Patterson's possible liability are an accurate reflection
of the law. Patterson, as Mr. Mitchell's employer, would be liable for his
actions under the theory of respondeat superior. If Mr. Mitchell breached a
duty to the Appellants, then Patterson is liable under the theory of
respondeat superior. If Mitchell did not breach a duty to the Appellants then
no degree of negligence on the part of Patterson in hiring Mitchell would
make Patterson liable to the Appellants. . . . The court did not err in using its
discretion to omit Appellants' requested jury instructions regarding negligent
hiring and training because they were not appropriate in this case.
Libersat, 772 So. 2d at 179.
V. PROBLEM (for discussion)
Imagine that a drug manufacturer fails to warn of the risks of diabetes that its drug
poses. The drug increases the risk of contracting diabetes by 25%.
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Part 1: A patient who has taken the drug, but has not yet been diagnosed
with diabetes, sues the drug manufacturer for failure to warn.
Part 2: A patient who has taken the drug and contracted diabetes sues the
drug manufacturer for failure to warn. The probability that the drug caused
plaintiff’s diabetes is 20%, i.e., 25 (those with diabetes due to the drug) / 125
(total population with diabetes).
Part 3: Suppose that the probability in Part 2 is 60% rather than 20%?
Should there be liability in any of the three parts? If so, for how much?
A. National:
1. Rejection of recovery for increased risk: Metro-North Commuter
Railroad Co. v. Buckley, 521 U.S. 424 (1997) (decision based on Federal
Employers Liability Act); DeStories v. City of Phoenix, 744 P.2d 705 (Ariz.
Ct. App. 1987) (asbestos-exposed workers without disease could not
recover); Capital Holding Corp. v. Bailey, 873 S.W.2d 187 (Ky. 1994). But
cf. Mauro v. Raymark Industries, Inc., 561 A.2d 257 (N.J. 1989) (holding
that plaintiff could recover for increased risk of future disease but only when
there was sufficient proof that the disease was more likely than not to occur).
2. The conflict between the academics and the courts. Academics
championing proportional liability, especially when the probability is 50%
or less. Compare, e.g., David Rosenberg, The Causal Connection in Mass
Exposure Cases: A ‘Public Law’ Vision of the Tort System, 97 HARV. L.
REV. 849 (1984) with, e.g., Allison v. McGhan Med. Corp., 184 F.3d 1300,
1315 n.16 (11th Cir. 1999) (breast-implant case; relative risk of 2.0 is the
threshold for an inference of specific causation; relative risk of 1.24 is
insufficient); Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1320
(9th Cir. 1995) (applying California law) (requiring that plaintiff
demonstrate a relative risk of 2.0); In re Breast Implant Litig., 11 F. Supp.
2d 1217 (D. Colo. 1998) (plaintiff must demonstrate more than a doubling of
risk of disease by defendant’s agent); Pick v. Am. Med. Sys., Inc., 958 F.
Supp. 1151, 1160 (E.D. La. 1997) (stating that a relative risk of 2.0 implies a
50% probability of specific causation, but acknowledging that a study with a
lower relative risk is admissible, if not sufficient to support a verdict on
causation); Sanderson v. Int’l Flavors & Fragrances, Inc., 950 F. Supp. 981,
1000 (C.D. Cal. 1996) (relative risk of 2.0 is a threshold for plaintiff to
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prove specific causation); Hall v. Baxter Healthcare Corp., 947 F. Supp.
1387, 1403 (D. Or. 1996) (“plaintiffs must be able to show a relative risk of
greater than 2.0”).
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