Infringement
of a patent consists of the unauthorized making, using, offering for
sale or selling any patented invention within the United States or United
States Territories, or importing into the United States of any patented
invention during the term of the patent. If a patent is infringed, the
patentee may sue for relief in the appropriate Federal court. The patentee
may ask the court for an injunction to prevent the continuation of the
infringement and may also ask the court for an award of damages because
of the infringement. In such an infringement suit, the defendant may
raise the question of the validity of the patent, which is then decided
by the court. The defendant may also aver that what is being done does
not constitute infringement. Infringement is determined primarily by
the language of the claims of the patent and, if what the defendant
is making does not fall within the language of any of the claims of
the patent, there is no literal infringement.
Suits
for infringement of patents follow the rules of procedure of the Federal
courts. From the decision of the district court, there is an appeal
to the Court of Appeals for the Federal Circuit. The Supreme Court may
thereafter take a case by writ of certiorari. If the United States Government
infringes a patent, the patentee has a remedy for damages in the United
States Court of Federal Claims. The Government may use any patented
invention without permission of the patentee, but the patentee is entitled
to obtain compensation for the use by or for the Government.
The
claims define the scope of protection for a patent afforded to the actual
inventor. Patent law requires the applicant to swear, or affirm, that
he believes himself to be the true inventor of the art, machine, or
improvement, for which he asks for a patent; and further that he shall
deliver a written description of his invention, in such full, clear,
and exact terms, that any person, acquainted with the art, may know
how to construct and use the same. The reason for this is to guard the
public against unintentional infringements of the patent, and to enable
the public to make an improvement that does not infringe your patent.
When an accused device possess every limitation of a claim in your patent,
then that device or process has comitted literal infringement of your
patent. However, the language in the patent claims may not capture every
nuance of the invention or describe with complete precision the range
of its novelty. If patents were always interpreted by their literal
terms, their value would be greatly diminished. Unimportant and insubstantial
substitutes for certain elements could defeat the patent, and its value
to inventors could be destroyed by simple acts of copying. For this
reason, the clearest rule of patent interpretation, literalism, may
conserve judicial resources but is not necessarily the most efficient
rule. The scope of a patent is not limited to its literal terms but
instead embraces all equivalents to the claims described.
In this way, a balance between the two competing policies behind the
enforcement of patent rights: (1) to protect the inventors right
to exclude others who might steal the product of his work by making
equivalent modifications, and (2) to provide clear notice to the public
of the inventions boundaries.
The
Patent Office has no jurisdiction over questions relating to infringement
of patents. In examining applications for patent, no determination is
made as to whether the invention sought to be patented infringes any
prior patent. An improvement invention may be patentable, but it might
infringe a prior unexpired patent for the invention improved upon, if
there is one.
Claim
Interpretation
For
a patent to be enforced, the claims must be interpreted by the courts
during infringement lawsuits. The case law governing claim interpretation
is very complex; however, some important aspects are discussed below. The
purpose of claims is not to explain the technology or how it works,
but to state the legal boundaries of the patent grant. A claim is not
"indefinite" simply because it is hard to understand when
viewed without benefit of the specification.
Claim
interpretation is the process of giving proper meaning to the claim
language. Claim language, after all, defines claim scope. Therefore,
the language of the claim frames and ultimately resolves all issues
of claim interpretation. In determining the meaning of disputed claim
terms, however, a construing court considers the descriptions in the
rest of the patent specification, the prosecution history, and relevant
extrinsic evidence.
That
is, a patent claim is construed by examining the claim in the context
of the specification, drawing on the specification for an understanding
of what is covered by the claim, and looking to the rejections, explanations,
and revisions that comprise the record of the patent examination. The
subject matter of the invention and its delineation in the claims is
construed as it would be understood by persons knowledgeable in the
field of the invention. Thus, a technical term is taken to have the
meaning that it would ordinarily have in the field of the invention,
unless it is shown that the inventor used the term with a special meaning
and that persons of skill in the field would so understand the usage.
To
learn the necessary context for understanding the claim language a construing
court may consult other sources, including the patent specification,
the administrative record of patent acquisition, expert commentary from
those of skill in the art, and other relevant extrinsic evidence. In
other words, a construing court does not accord the specification, prosecution
history, and other relevant evidence the same weight as the claims themselves,
but consults these sources to give the necessary context to the claim
language.
The
general rule is, that terms in the claim are to be given their ordinary
and accustomed meaning. General descriptive terms will ordinarily be
given their full meaning; modifiers will not be added to broad terms
standing alone. In short, a court must presume that the terms in the
claim mean what they say, and, unless otherwise compelled, give full
effect to the ordinary and accustomed meaning of claim terms. In order
to overcome this heavy presumption in favor of the ordinary meaning
of claim language, case law makes clear that a party wishing to use
statements in the written description to confine or otherwise affect
a patent's scope must, at the very least, point to a term or terms in
the claim with which to draw in those statements. That is, claim terms
cannot, generally, be narrowed by reference to the written description
or prosecution history unless the language of the claims invites reference
to those sources. In other words, there must be a textual reference
in the actual language of the claim with which to associate a proffered
claim construction.
Case law demonstrates two main situations where a sufficient reason
exists to require the entry of a definition of a claim term other than
its ordinary and accustomed meaning. The first arises if the patentee
has chosen to be his or her own lexicographer by clearly setting forth
an explicit definition for a claim term. The second is where the term
or terms chosen by the patentee so deprive the claim of clarity that
there is no means by which the scope of the claim may be ascertained
from the language used. For example, if a disputed claim term is a term
with no previous meaning to those of ordinary skill in the prior art,
its meaning, then, must be found elsewhere in the patent, whereby the
specification is used for guidance when the meaning of a claim term
is in doubt. The written description can supply understanding of unclear
claim terms, but should never trump the clear meaning of claim terms.
Hence, to avoid a potential limitation of claim scope, a claim term
should not be so amorphous that one of skill in the art can only reconcile
the claim language with the inventor's disclosure by recourse to the
specification. In these two circumstances, a term or terms used in the
claim invites or indeed, requires reference to intrinsic (i.e., the
claims, the written description, and, if in evidence, the prosecution
history) , or in some cases, extrinsic (e.g., treatises, technical references,
and expert testimony), evidence. Reference to extrinsic evidence is
generally proper when intrinsic evidence cannot resolve ambiguity in
claim language, to determine the scope of the claim language.
The language in the patent claims may not capture every nuance of the
invention or describe with complete precision the range of its novelty.
If patents were always interpreted by their literal terms, their value
would be greatly diminished. Unimportant and insubstantial substitutes
for certain elements could defeat the patent, and its value to inventors
could be destroyed by simple acts of copying. For this reason, the clearest
rule of patent interpretation, literalism, may conserve judicial resources
but is not necessarily the most efficient rule. The scope of a patent
is not limited to its literal terms but instead embraces all equivalents
to the claims described.
Doctrine
of Equivalents
The constitutional purpose of patent law is to "promote the
Progress of Science and useful Arts" by granting inventors exclusive
rights to their inventions for a limited period of time. The judicially
created doctrine of equivalents has long played an important, albeit
controversial role in the realm of patent law. It strives to strike
a balance between the two competing policies behind the enforcement
of patent rights: (1) to protect the inventor's right to exclude others
who might steal the product of his work, and (2) to provide clear notice
to the public of the invention's boundaries.
The doctrine of equivalents is an equitable doctrine established
by the courts to protect patented inventions. In order to find that
a patent has been infringed (literal infringement), every element of
the patented claim must be found in the infringing device. Thus, a
copyist can avoid literal infringement by making changes so that his
or her device does not have the exact elements disclosed in the patented
claim. Any discrepancy between the patented claim and the accused device
will negate a finding of literal infringement.
However, in order to protect patent owners from copyists
stealing the patented invention by making small or insubstantial changes
to the invention, the Supreme Court established the principle of infringement
under the doctrine of equivalents. This doctrine allows a court to
find infringement if the elements of the accused device are "insubstantially"
different from those disclosed in the patent. Hence, the doctrine
of equivalents allows the patentee to claim those insubstantial alterations
that were not captured in drafting the original patent claim but which
could be created through trivial changes. When, however, the patentee
originally claimed the subject matter alleged to infringe but then narrowed
the claim in response to a rejection, he may not argue that the surrendered
territory comprised unforeseen subject matter that should be deemed
equivalent to the literal claims of the issued patent.
When the Court in Winans v. Deninead (15 How. 330, 343 (1854))
first adopted what has become the doctrine of equivalents, it stated
that "[t]he exclusive right to the thing patented is not secured,
if the public are at liberty to make substantial copies of it, varying
its form or proportions." The debate continued in Graver Tank &
Mfg. Co. v. Linde Air Products Co. (339 U.S. 605, 607 (1950)), where
the Court reaffirmed the doctrine. Graver Tank held that patent claims
must protect the inventor not only from those who produce devices falling
within the literal claims of the patent but also from copyists who "make
unimportant and insubstantial changes and substitutions in the patent
which, though adding nothing, would be enough to take the copied matter
outside the claim, and hence outside the reach of law." More recently,
in Warner-Jenkinson, the Court reaffirmed that equivalents remain a
firmly entrenched part of the settled rights protected by the patent.
Because of the inherent uncertainty in the doctrine of equivalents,
courts have exercised their equitable powers to limit the doctrine.
An important limit is the principle of prosecution history estoppels.
This doctrine relates to the amendments, statements, arguments, and
representations made by the patent applicant during the course of obtaining
a patent. Any
statement that limits the scope of the patent made for "a reason
related to patentability" is binding and the applicant will be
forbidden (estopped) from later attempting to argue that the limitation
does not exist.
The courts are continually struggling with the crucial issue
of when should the doctrine of equivalents be applied, and at what point
is the claim language of a patent stretched too far; Festo
is only the latest case of many on this issue.
Generally, a particular structure can be deemed outside the
reach of the doctrine of equivalents because that structure is clearly
excluded from the claims whether the exclusion is express or implied.
Courts
generally recognize that their case law and reasoning places a premium
on forethought in patent drafting, which may lead to higher costs of
patent drafting and prosecution. However, in recent years, they consider
that an alternative rule -- that is, allowing broad play for the doctrine
of equivalents to encompass foreseeable variations, not just of a claim
element, but of a patent claim -- also leads to higher costs. Society
at large would bear these latter costs in the form of virtual foreclosure
of competitive activity within the penumbra of each issued patent claim.
An
accused device may infringe a claim under the doctrine of equivalents
if it performs substantially the same overall function or work, in substantially
the same way, to produce substantially the same overall result as the
claimed invention. To be an equivalent, the element substituted in the
accused device for the element set forth in the claim must not be such
as would substantially change the way in which the function of the claimed
invention is performed. Under the doctrine of equivalents, the accused
device and the claimed invention cannot work in `substantially the same
way' if a limitation (including its equivalent) is missing. Moreover,
the doctrine of equivalents does not require a one to one correspondence
between components of the accused device and the claimed invention.
An accused device may infringe under the doctrine of equivalents even
though a combination of its components performs a function performed
by a single element in the patented invention. The accused device must
nevertheless contain every limitation or its equivalent. Equivalency
can also exist when separate claim limitations are combined into a single
component of the accused device. One to one correspondence of components
is not required, and elements or steps may be combined without ipso
facto loss of equivalency. Each case must be decided in light of the
nature and extent of the differences between the accused device and
the claimed invention, on the equitable principles of the doctrine of
equivalents. An "equivalent" of a claim limitation cannot
substantially alter the manner of performing the claimed function. Where
an accused device performs substantially the same function to achieve
substantially the same result but in a substantially different manner,
there is no infringement under the doctrine of equivalents.
Festo
A court case of Festo Corp. v. Shoketsu Kinzoki Kogyo
Kabushiki Co (SMC Corp.), referred to as "Festo", has recently challenged prior doctrine
of equivalence practice. In this case Festo's patent claimed a
device with a pair of sealing rings and the defendant's device only
employed one sealing ring. In the court's view, such differences were
insubstantial, and thus the court found the defendant liable for patent
infringement under the doctrine of equivalents.
The spirit behind the Festo decision is that patent laws
"promote the Progress of Science and useful Arts" by rewarding
innovation with a temporary monopoly. U. S. Const., Art. I, §8,
cl. 8. The monopoly is a property right; and like any property right,
its boundaries should be clear. This clarity is essential to promote
progress, because it enables efficient investment in innovation. Moreover,
a patent holder should know what he owns, and the public should know
what he does not. For this reason, the patent laws require inventors
to describe their work in "full, clear, concise, and exact terms,"
35 U. S. C. §112, as part of the delicate balance the law attempts
to maintain between inventors, who rely on the promise of the law to
bring the invention forth, and the public, which should be encouraged
to pursue innovations, creations, and new ideas beyond the inventor's
exclusive rights.
Although both infringement under the doctrine of equivalents
and prosecution history estoppels appear to complement one another,
there are interesting questions regarding the interface between the
two doctrines. For example, if an element has been limited by an amendment,
is prosecution history estoppel a complete bar on all possible equivalents
to this element, or is there a range of equivalents still available
in an infringement analysis? Moreover, is an equivalent structure discovered
after the submission of the amendment also barred by prosecution history
estoppel, or does the estoppel apply only to those equivalents specifically
disclaimed in the amendment?
Generally, practitioners should try to obtain allowance of
claims that not only will satisfy a patent examiner, but also will be
found both valid and infringed (and enforceable) in litigation. The
practitioner therefore should consider how courts likely will construe
claims and what impact actions taken during patent prosecution likely
will have on that construction. In particular, Festo has placed a premium
on obtaining valid and enforceable claims with a minimum of prosecution
history. In other words, practitioners should now also strive to draft
original claims that are in condition for allowance without need for
amendment. This patent practice is in stark contrast to prior approaches
that advised clients not to search too hard for prior-art, and started
with weak initial claims that were expected to be amended to good form
during prosecution.
The
courts conclusion that prosecution history estoppel arises when a claim
is narrowed to comply with §112 gives rise to the second question
presented: Does the estoppel bar the inventor from asserting infringement
against any equivalent to the narrowed element or might some equivalents
still infringe? The Court of Appeals held that prosecution history estoppel
is a complete bar, and so the narrowed element must be limited to its
strict literal terms. Based upon its experience the Court of Appeals
decided that the flexible-bar rule is unworkable because it leads to
excessive uncertainty and burdens legitimate innovation. For the reasons
that follow, the court disagreed with the decision to adopt the complete
bar. Though prosecution history estoppel can bar challenges to a wide
range of equivalents, its reach requires an examination of the subject
matter surrendered by the narrowing amendment.