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1. Introduction
This is a comment on the case Warner Jenkinson Co., Inc. v. Hilton
Davis Chemical Co. decided by U. S. Supreme Court on March 3, 1997, 117
S. Ct. 1040 (US 1997), which deals with the doctrine of equivalents, or
the infringement under the doctrine of equivalents.
In the United States, the doctrine of equivalents is not a
statutory provision in the patent law, but a set of rules established by
a series of cases when courts decide infringement of patent. The modern
doctrine of equivalents in the United States was set out by the Supreme
Court case Graver Tank & Mfg. Co. v. Linder Air Products Co., 339 U. S.
605 (1950). One passage often quoted in the case is read as follows:
What constitutes of equivalency must be determined against the
context of the patent, the prior art, and the particular circumstances
of the case. Equivalence, in the patent law, is not the prisoner of a
formula and is not an absolute to be considered in a vacuum. It does not
require complete identity for every purpose and in every respect. In
determining equivalents, things equal to the same thing may not be equal
to each other and, by the same token, things for most purposes different
may sometimes be equivalents. Consideration must be given to the purpose
for which an ingredient is used in a patent, the equalities it has when
combined with the other ingredients, and the function which it is
intended to perform. An important factor is whether persons reasonably
skilled in the art would have known of the interchangeability of an
ingredient not contained in the patent with one that was.
After Graver Tank, U. S. Supreme Court had not decided any case
relating to the doctrine of equivalents in almost 50 years. In that
period, the inferior courts gradually diverged from their opinions in
applying the doctrine of equivalents, whereas intense debates were
occurred among judges, patent attorneys, and professors. Therefore, the
Supreme Court restated some basic elements concerning the doctrine of
equivalents in Hilton Davis, and cleared many issues relating to the
debates.
2. "Element by Element" Test
How to interpret a patent claim is a key issue in deciding whether
an infringement of the patent occurred there. When the Federal Circuit
decided Hilton Davis Chemical Co., v. Warner Jenkinson Co., 62 F. 3d
1512, (Fed. Cir. 1995), it used "insubstantial difference" test to
decide whether the accused product or process infringed the patented
product or process. That is, if the accused product or process as a
whole is the same one as the product or process covered by the patent,
there is an infringement under the doctrine of equivalents, otherwise
there is no infringement under the doctrine of equivalents. However,
this is more close to the central claiming principle in interpretation
of a patent claim, which is contrary to the peripheral claiming
principle used by U. S. courts for a long period.
In Hilton Davis, the Supreme Court struck down the insubstantial
difference test and affirmed the element by element test put forward by
Judge Nies of Federal Circuit in a dissenting opinion. The Supreme Court
stated:
Each element contained in a patent claim is deemed material to
defining the scope of the patented invention, and thus the doctrine of
equivalents must be applied to individual elements of the claim, not to
the invention as a whole. It is important to ensure that the application
of the doctrine, even as to an individual element, is not allowed such
broad play as to effectively eliminate that element in its entirety.
This is the element by element test and the typical peripheral
claiming principle. The Supreme Court said confidently that "So long as
the doctrine of equivalents does not encroach beyond the limits just
described, or beyond related limits to be discussed infra, we are
confident that the doctrine will not vitiate the central functions of
the patent claims themselves."
In deciding Hilton Davis Chemical Co. v. Warner Jenkinson Co., the
Federal Circuit and the parties argued whether the "function-way-result"
test is a suitable method for determining equivalence, or whether the
"insubstantial differences" approach is better. The Supreme Court stated
that those linguistic frameworks are less important than "element by
element" test in applying the doctrine of equivalents. "An analysis of
the role played by each element in the context of the specific patent
claim will thus inform the inquiry as to whether a substitute element
matches the function, way, and result of the claimed elements, or
whether the substitute element plays a role substantially different from
the claimed element." Therefore, the Supreme Court has the
"insubstantial difference" and "function-way-result" as methods or
approaches within the "element by element" test in determining
equivalence, rather than the ones that are independent of, or substitute
of "element by element" test.
3. Prosecution History Estoppel
Prosecution history estoppel is a legal limit to the doctrine of
equivalents to the effect that any surrender of subject matter during
patent prosecution to avoid the prior art may not be recovered by the
patent owner later, even if it is equivalent to the matter expressly
claimed.
Prosecution history estoppel is closely connected to the procedure
of patent examination. In this case, although Hilton Davis Chemical Co.
filed an application with no limit on the pH in its patent claim, it
narrowed the pH levels between 6.0 and 9.0 in responding to the
requirement by the patent examiner. To add the upper limit of 9.0 is to
distinguish a prior patent, whereas the reason for adding the lower
limit of 6.0 is unclear.
Because the process of Warner Jekinson Co. has a pH of 5.0, it
argued that Hilton Davis Chemical might not recover any subject matter
it surrendered during the patent prosecution, regardless of the reason
for such surrender. The Supreme Court believed that, however, Warner
Jekinson Co. "reaches too far in arguing that the reason for an
amendment during patent prosecution is irrelevant to any subsequent
estoppel. In each of our cases cited by petitioner and by the dissent
below, prosecution history estoppel was tied to amendment made to avoid
the prior art, or otherwise to address a specific concern--such as
obviousness--that arguably would have rendered the claimed subject
matter unpatentable." Thus only may the subject matter surrendered in
the prosecution to avoid the prior art not be recaptured by applying the
doctrine of equivalents.
In this respect, the reason for surrendering any subject matter in
the prosecution is very important. The Patent Office may request an
amendment of a claim for various reasons, but "certain reasons for a
claim amendment may avoid the application of prosecution history
estoppel is not tantamount to holding that the absence of a reason for
an amendment may similarly avoid such an estoppel." Because the reason
for Hilton Davis to add a lower pH limit of 6.0 is not clear, the
Supreme Court remanded the case to the Federal Circuit.
4. The Proper Time for Evaluating Equivalency
A patent claim has two functions: defining an invention and
providing a public notice. Warner Jekinson Co. argued in petition that
in order to minimize conflict with the notice function of patent claims,
the doctrine of equivalents should be limited to equivalents that are
disclosed within the patent itself. This means that the proper time for
evaluating equivalency is the time of application or the time when a
claim is finalized. A milder argument by dissenters in Federal Circuit
is that the doctrine should be limited to equivalents that were known at
the time the patent issued.
The Supreme Court hold that "insofar as the question under the
doctrine of equivalents is whether an accused element is equivalent to a
claimed element, the proper time for evaluating equivalency-and thus
knowledge of interchangeability between elements-is at the time of
infringement, not at the time the patent was issued."
This time point for evaluating equivalency is very important to
patent owner. In the patent examination, the patent office may ask the
applicant to exclude the element from the claim that is equivalent to or
obvious to a prior art and thus set the scope of the patent. From that
time on, other persons may improve the invention further along with the
development of specific technology. If the improvement is a nonobvious
one, it is a new invention and may get a new patent. If it is an obvious
one, it is still within the scope of the original patent and is
protected by applying the doctrine of equivalents. Apparently if the
time for evaluating equivalency is the time of application or issuing
patent, the patent owner may not get that kind protection, and the
purpose of the patent law to protect invention and encourage invention
will be jeopardized.
5. The Intent of the Alleged Infringer
Warner Jekinson Co. developed its process independently and did not
learn the patent owned by Hilton Davis Co. until it begun commercial use
of its process. Thus Warner Jekinson Co. argued in petition that the
intent of the alleged infringer should be explored before the
application of the doctrine of equivalents.
Graver Tank did leave room for the inclusion of intent in applying
the doctrine of equivalents, such as referring to the problem of an
"unscrupulous copyist" and "piracy". In Addressing to this, Federal
Circuit distinguished copying, designing around a patent, and
independent experimentation. In disagreeing with this, the Supreme Court
stated: "This explanation leaves much to be desired. At a minimum, one
wonders how ever to distinguish between the intentional copyist making
minor changes to lower the risk of legal action, and the incremental
innovator designing around the claims, yet seeking to capture as much as
is permissible of the patented advance."
The Supreme Court believed that the better way is whether there is a
"known interchangeability" between the patented element and the accused
element in the eye of one skilled in the art. If it is, or the accused
one is a substitute of the patented one, an infringement exists; if it
is not, or the accused one is not a substitute, an infringement does not
exist. Because this method has no relationship with the subjective
condition of the alleged infringer, it is an objective method in
applying the doctrine of equivalents.
The Supreme Court concludes that "Although Grave Tank certainly
leaves room for petitioner's suggested inclusion of intent based
elements in the doctrine of equivalents, we do not read it as requiring
them. The better view, and the one consistent with Graver Tank's
predecessors and the objective approach to infringement, is that intent
plays no role in the application of the doctrine of equivalents."
6. Conclusion
This paper is intended to introduce the doctrine of equivalents in
U. S. patent law into Chinese legal circle. Although many Chinese
scholars have explored the doctrine of equivalents, and many Chinese
Judges have applied the doctrine of equivalents to decide cases, those
are preliminary explorations and tentative applications. In this
respect, Hilton Davis discussed many issues in a deep going way
concerning the doctrine of equivalents, and is worth of Chinese scholars
and judges to take reference from it. It is hoped that this paper will
further the understanding of the doctrine of the equivalents by Chinese
scholars and judges and thus improve the research and the judiciary. |