The Limited Monopoly®
Interpreting Patent Claims The Meaning of Those Strange Little Sentences
by Robert Gunderman, PE and John Hammond, PE
What’s in a Claim Anyhow
Claims, those strangely constructed sentences at the end of a
patent or patent application, usually get all of the attention.
They define what an invention is, and is not. While seemingly
simple enough, words have their limitations and can be
interpreted in differing ways, and the interpretation of claim
language is the topic of most
struggles within the Patent
Office during prosecution
or post-grant challenges to
validity, as well as in the
courts during litigation.
There are differing standards
and approaches to interpreting
claims, each of which is
important to understand if
you are involved with patents.
Claim interpretations may
vary depending upon the
venue where arguments are
being made. While many
books have been written on
this topic as well as countless
litigation and prosecution related documents, our goal is to
present a very brief summary of how claims may be interpreted.
(If an initial primer on patent claims in general is needed, that
can be found in our two part series “Staking Your (Patent)
Claims” 1,2.)
Teflon®, a Claim That Nothing Can Stick To
The more words in a claim, the narrower the scope of the claim
tends to be. Of course more words mean there is more to
interpret, and a lengthy claim, while often narrow in scope,
provides ample opportunity for scrutiny of each and every word.
And then there is the original patent for Teflon® (a registered
trademark of E.I. DuPont de Nemours and Company) granted
in 1941 to Roy J. Plunkett and assigned to Kinetic Chemicals,
Inc. of Wilmington, Delaware (a subsidiary of E.I. DuPont de
Nemours and Company). Claim 1 reads simply “Polymerized
tetrafluoroethylene.” With a claim like that, there is not much
left for the imagination to interpret. Most claims, however,
don’t have such brevity and are subject to interpretation.
10 | The ROCHESTER ENGINEER | APRIL 2015
Different Standards for Prosecution and Litigation
When interpreting patent claims, different standards apply
depending on whether you are prosecuting your patent
application before an Examiner in the United States Patent
and Trademark Office or litigating an issued patent in court.
A third category, post-grant validity challenges before the
USPTO Patent Trial and
Appeal Board, has drawn
from both standards. A solid
understanding of both of
these standards is important
when drafting claims in a
patent application to ensure
successful prosecution, as
well as to give claims the
best wording possible for
any future litigation. Claim
interpretation, the act or
process of defining the
meaning of a patent claim,
may be straightforward, or it
may be full of complexities
and ambiguities. Knowing
the various ways that a claim
can be interpreted allows a patent practitioner to write a more
robust claim or scrutinize an existing claim.
The Prosecution Standard
Claims in a pending patent application are eventually examined
for patentability. During examination, the pending claims in
a patent application must be given their broadest reasonable
interpretation in light of the specification as it would be
interpreted by one of ordinary skill in the art.3 Furthermore,
the words of a claim must be given their plain meaning unless
this meaning is inconsistent with the specification. The plain
meaning of a word is the ordinary and customary meaning
given to the term by those of ordinary skill in the art at the
time of the invention. The specification, drawings, prior
art, and the words of the claims themselves are all used to
determine the meaning of a claim. However the specification
is the best source of meaning, and is relied on heavily by the
Examiner in determining patentability. It is improper for an
Examiner to import claim limitations from the specification
into the claims.4
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y
Additionally, words of a claim are given their “plain meaning”
unless that meaning is inconsistent with the specification5.
The Applicant may also be his own “lexicographer,” defining
a term in the specification in such a way that it supersedes
the plain meaning of the term.6 There are other rules of
claim interpretation in prosecution as well. For example,
the preamble of the claim may be non-limiting. Other words
in a claim, such as transitional phrases like “comprising” or
“consisting of ” have very specific meanings and are used to
interpret the claims.
The Litigation Standard
In litigation, claims of issued patents are commonly interpreted
in view of the patent specification, the prosecution history
record, the prior art, and other claims in the patent itself. In
addition, evidence can be provided to attempt to sway the
interpretation in a desired direction. Often interpretation of
a single word in a claim can make or break a desired litigation
outcome. Court cases over the years have molded and shaped
claim interpretation, and continue to do so. The ordinary
meaning of a claim term is often used to interpret that claim,
and dictionaries are commonly used to assist with that ordinary
meaning. Other outside references may also be consulted, the
use of which is referred to as extrinsic evidence.
The use of intrinsic evidence such as the patent specification
itself, claim language, and prosecution history is generally
heavily relied on. In fact, the U.S. Court of Appeals for the
Federal Circuit considers the patent specification to be the
best source of guidance for claim meaning, and the Court
relies heavily, but not exclusively, on the patent specification.
Prosecution history, the written record of negotiation between
the patent examiner and patent practitioner, is also used to
show the scope of the invention and how it was understood.
The claims themselves are also used to interpret other claims
in the patent. The words surrounding a term in question
as well as usage of the term in other claims are all helpful in
interpreting that claim.
Furthermore, the doctrine of claim differentiation looks
at the relative scope of each claim in relation to the others.
Essentially, this doctrine says that two claims in the same patent
will not have identical scope, but there is in all likelihood an
intended difference in scope between the two. For example,
a dependent claim that introduces a further limitation implies
that this further limitation was not present in the independent
claim to which it refers. This concept is not only important
to infringement, but also to validity. If an independent claim
is broader than the dependent claim to which it refers, the
broadness of that independent claim not only makes it the
easier of the two to infringe, it also makes it more vulnerable
to a validity challenge since its broadness makes it closer to the
prior art than its narrower dependent claim counterpart.
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While both extrinsic evidence and intrinsic evidence are
important to claim interpretation, extrinsic evidence is usually
less significant than intrinsic evidence such as the patent
specification itself in claim interpretation.
Making a Mountain out of a
Word and Sorting it Out at a Markman Hearing
This article provides a brief overview of the various concepts
of claim interpretation. A mountain of evidence and
documentation can easily be prepared in defense of a certain
position on claim interpretation, or even the interpretation of
just one pivotal word in a patent claim. The stakes in patent
litigation are usually high, and often the importance of a broad,
well worded claim during prosecution is key to a company’s
success, or at least the success of a new product. Getting the
interpretation of a claim sorted out is often no simple task.
One step used by the courts in determining the meaning of
claim terms is a Markman hearing. This is a pretrial hearing in
U.S. Federal District Court where a judge considers evidence
from both parties regarding the asserted meaning of claim
terms. These hearings are named after the Supreme Court case
Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996).
Needless to say, claim interpretation can be contentious and
costly. Good practices in prosecution before the patent issues
can help if there is ever the need to litigate.
1. The Limited Monopoly® April 2009
2. The Limited Monopoly® May 2009
3. MPEP §2111, 37 CFR 1.75(d)(1)
4. MPEP §2111.01(II)
5. MPEP §2111.01(I and III)
6. MPEP §2111.01(II)
7. MPEP §2111.01(IV)
Authors Robert D. Gunderman P.E. (Patent Technologies, LLC
www.patentechnologies.com) and John M. Hammond P.E.
(Patent Innovations, LLC www.patent-innovations.com) are
both registered patent agents and licensed professional engineers.
They offer several courses that qualify for PDH credits. More
information can be found at www.patenteducation.com.
Copyright 2015 Robert Gunderman, Jr. and John Hammond
Note: This short article is intended only to provide
cursory background information, and is not
intended to be legal advice. No client relationship
with the authors is in any way established by this
article.
GRAPHIC CREDIT: Apples in the Marketplace. Robert
Gunderman.
APRIL 2015 | The ROCHESTER ENGINEER | 11