Center for Advanced Study & Research on Innovation Policy


CASRIP Newsletter - Winter 1997, Volume 4, Issue 1

U.S. Supreme Court Reversed and Remanded Federal Circuit Hilton Davis en banc Decision

On March 3, 1997, the U.S. Supreme Court handed down a long-awaited decision on the doctrine of equivalents.1 Although the Supreme Court agreed in principle with the Federal Circuit en banc majority that courts must automatically apply the doctrine of equivalents upon failing to find evidence of literal infringement, and that infringement under the doctrine of equivalents must be decided objectively, the Court nevertheless reversed the en banc decision and remanded the case to the Federal Circuit. The Court instructed the Federal Circuit to investigate the reason for introducing the disputed claim element during patent prosecution, and to particularly note the individual elements in determining whether all the elements were preserved in the accused device with respect to its function and effect on the entire patented invention. The Court disappointed patent professionals around the world by not affirming the en banc decision, which would have ended patent professionals' extended debates on the doctrine of equivalents.

The biggest disappointment was the Court's declination to consider whether the doctrine of equivalents should be applied by juries or judges; the Court stated that the resolution of the issue was unnecessary to answer the question presented in the case. Contrary to the expectation that the Court's analysis would focus on jury/judge roles in applying the doctrine, the Court acquiesced to the Federal Circuit majority's current view, and deferred the opportunity to attack the most interesting issue.

Overall, the Court did not clearly answer any of the extensively disputed issues defining the test for equivalents, nor did it clarify how the test should be applied. Instead, the Court merely suggested a direction, and left the resolution of these issues to the Federal Circuit and the government.

Test for Equivalency

The Supreme Court indicated a restrictive approach to analyzing infringement under the doctrine of equivalents, and emphasized the importance of confirming the presence of each claim element in the accused device. The Federal Circuit en banc Hilton Davis decision resurrected dead debates on whether equivalency must be shown on an element-by-element basis or on the invention as a whole. The en banc decision did not address this issue and the Federal Circuit's redefined "insubstantial difference" test suggests an "as a whole" approach, despite the Court's own Pennwalt en banc decision affirming an "element-by-element" approach.2

Showing a strong sympathy for the late Judge Nies' concern that the doctrine significantly reduces the definitional and public-notice functions of claims, the Court stressed that the doctrine of equivalents must be applied to individual elements of the claim, and not to the invention as a whole. However, the Court neglected to clarify the meaning of an essential concept, i.e., "element," by which to conduct the analysis on an element-by element basis.3 If an "element" means a limitation, and an element-by-element analysis is applied to require a strict correspondence of each component between the patented invention and the accused device as suggested in Pennwalt, infringement under the doctrine would not be much different from literal infringement. This would make the doctrine meaningless, because such a strict application would prevent courts from overcoming the form of claims. This also produces the unreasonable result that the Graver Tank Court tried to avoid by introducing the doctrine, i.e., "plac[ing] the inventor at the mercy of verbalism and would be subordinating substance to form."4

In cases after Pennwalt, the Federal Circuit found an "element" to be a combination of limitations.5 The same court also allowed for the flexibility of finding an equivalent of every limitation somewhere in the accused device6 to avoid the unreasonable result of subordinating substance to form.

The Court provided guidance by indicating that the application of the doctrine should focus on the role played by each element in the context of the specific patent claim. This analysis examines whether the substituted element functions in the substantially same way to produce the substantially same result as the claimed element.

Inevitably, such an analysis requires courts to examine whether the substitution of the disputed element substantially affects the overall function of the patented invention, and leads to another question: how should we define an "element-by-element" analysis so that it is distinct from an invention "as a whole" analysis?

It appears that the Court's resolution to maintain the doctrine of equivalents, while focusing on the preservation of each element, results from a compromise to balance competing interests involved in patent policy, rewarding inventors and giving clear notice to competitors. Lower courts, including the Federal Circuit, will be at a loss in formulating the test for equivalency, and making the application of the test uniform, unless the Supreme Court gives clear parameters on what extent the correspondence of limitations in a component is required between the patented invention and the accused device.

The situation that the Federal Circuit will face is readily predicted if one examines case law developments in European countries after the enactment of European Patent Convention Article 69. The language of Article 69 and its interpretation protocol reflect a compromise of member states which weigh competing interests differently. The United Kingdom, which places substantial weight on competitors' interests to receive clear notice - and parallels the Hilton Davis dissenters' view - wanted to limit the patent protection to that which can be literally interpreted from the claim language.

In contrast, Germany, which places more weight on inventors' interests in receiving appropriate rewards for their contributions _ and parallels the Hilton Davis majority view _ felt a need to secure protection beyond what is literally meant by the claim language. Unable to articulate a test representing the midway point between these two extreme views, Article 69's protocol simply provides that European patents' claims should not be interpreted to reflect either extreme view.7

Some member state courts and legal commentators interpreted Article 69 as requiring a strict correspondence between every limitation in respective components (as announced in Pennwalt), and to ban any so-called "partial infringement," i.e., Contrefaçon partielee under French law or Elementenschutz under German law.8 Other courts, including the French Supreme Court, and some French and many German legal commentators interpreted Article 69 to mean that it did not necessarily eliminate partial infringement.

Some commentators advocated a midway position, which classify claims into two categories: "combination claims," where all limitations collaboratively function to achieve the result of the invention; and "complex claims," where limitations independently function to produce the result. Only "complex claims," as opposed to "combination claims," were to enjoy partial protection.

The Federal Circuit faced similar controversies after Pennwalt. It will soon have to once again face the task of defining "element" in applying the doctrine on an "element-by-element" basis as instructed by the Supreme Court.

Prosecution History Estoppel

Another important point made by the Supreme Court is that prosecution history estoppel applies only where the amendment to exclude the infringing equivalent elements was made to maintain the patentability; patentees are responsible for establishing the reason so as to avoid the application of estoppel. If the record fails to reveal the reason for amendment, the reason is presumed to relate to patentability.

With respect to the patentee's possible rebuttal to overcome the presumption, the Court emphasized that proper deference must be given "to the role of claims in defining an invention and providing public notice, and to the primacy of the PTO in ensuring that the claims allowed cover only subject matter that is properly patentable in a proffered application."

Although evidence to establish the reason for amendment should be developed in future case law, this clarification of the burden of proof will significantly change the current U.S. practice of avoiding records of communication with the Patent Office during patent prosecution.9 Currently, U.S. attorneys prefer oral communications, and prefer to avoid discussions which clarify the features and advantages of the claimed invention compared to the prior art. This practice does not leave any record which can be used as a basis for prosecution history estoppel, and often proved difficult for European and Japanese attorneys. The Europeans and the Japanese tend to describe an invention with respect to its closest prior art.

With the clear burden for the reason of amendment on the patentee, the absence of a record on the reason for amendment would jeopardize the entire scope of equivalency. After Warner-Jenkinson, attorneys should ensure that they keep clear records on the reason for an amendment unrelated to patentability. Even if an amendment was made to overcome the prior art, attorneys should keep a good record of the discussion of distinctive features and advantages over the prior art; this would clarify the essential elements argued to overcome the prior art. Attorneys will then be able to argue that the substituted element is not related to the distinctive features and advantages of the invention. Thus the patentability over the prior art will not be affected.

For example, in Warner-Jenkinson, although the record indicates that the disputed pH range was introduced to overcome the prior art, the Supreme Court gave the patentee an opportunity to establish the reason why the lower limit of the pH range was introduced during the prosecution. Had the prosecution included a record on why the lower limit was introduced, or at least a record of clear discussion that only the upper limit was necessary to distinguish the prior art and produce an advantage over the prior art, the patentee would have readily established that the lower limit was introduced for a reason other than overcoming the prior art. In short, the Supreme Court's ruling of placing the burden of proof on patentees significantly improves current practice. It encourages disclosure of information for understanding the invention, and significantly contributes to the patent goal of disseminating technical information.

Points that the Supreme Court did not clearly address which may introduce confusion in applying this redefined prosecution history estoppel are: (1) whether the estoppel applies if the amendment was made to overcome an enablement rejection; and (2) how the estoppel doctrine relates to the Wilson Sporting Goods prior art limitation doctrine.10 With respect to the first point, although the court cited only precedents where amendments were made to overcome the prior art, the Court repeatedly mentioned that the application of estoppel should be limited to a situation where an amendment was made to maintain the patentability in general. Thus, it is not clear whether the Court meant to include a situation where an amendment was made to overcome an enablement rejection.11

As indicated by the typical facts in the Japanese Osaka High Court Genentech case,12 it is often very difficult and sometimes even impossible for a patentee to draft a claim with a reasonable breadth of scope if the claim directs to a pioneer invention in a highly-advanced field of technology. When the general knowledge of those skilled in the particular field of technology is very limited, claims to cover embodiments - the operation of which are unpredictable - are often rejected for lack of enablement. To overcome the rejection, patentees are often required to limit the claim to cover only predictable embodiments, which may result in a claim covering only disclosed embodiments.

If a competitor replaces a claimed element with a later developed well-known equivalent, the elimination of the doctrine of equivalents because of the amendment made to meet the enablement requirement would deprive the patentees of the last resort of securing a fair reward for their significant contribution. To avoid this unreasonable result, prosecution history estoppel should apply only to the situation where an amendment is made to overcome the prior art for novelty and nonobviousness rejections.

If the reason for applying prosecution history estoppel is limited to the situation for overcoming prior art, the resulting limitation of the doctrine of equivalents through prosecution history estoppel significantly overlaps with that of the prior art limitation doctrine in Wilson Sporting Goods.13 The Court did not discuss whether this redefined prosecution history estoppel will replace the prior art limitation or if both doctrines will co-exist.

The two doctrines may be distinguished by taking the position that the Wilson Sporting Goods doctrine applies only to prior art which was not cited during prosecution. However, if the two doctrines are understood to share the same principle, they should be merged so as to avoid confusion.

With respect to the Wilson Sporting Goods doctrine, authorities have split after Hilton Davis on which party bears the burden of proof for establishing the patentability of the accused device.14 If the Court's instruction is interpreted to relate to the claims' notice function and the PTO's interests in ensuring the patentability of issued patents regarding the doctrine, the burden should be on the patentee with the same degree of deference given to the application of prosecution history estoppel.

As a comparative law note, the U.S. Supreme Court contributed to the harmonization of patent claim interpretation by emphasizing the importance of the "known interchangeability" test, which parallels the test for determining equivalency used by Japanese and German courts.

The Court also edged U.S. patent claim interpretation back to the peripheral claim definition theory, thus moving U.S. patent claim interpretation closer to Japanese claim interpretation in limiting the application of the doctrine of equivalents to an element-by-element basis.15 By doing so, the Court attempted to curb the Federal Circuit's pro-patent tendency, and to prevent the logically extreme result, which would be a restructuring of U.S. patent claim interpretation under the central claim definition theory and a merging with its German counterpart.

No one knows whether the Federal Circuit will follow the Supreme Court's lead. In a similar situation in Germany, the German courts maintained a broad claim interpretation approach although the German Patent Law was revised to meet the requirement under EPC Article 69. The well-established pro-patent tradition dies hard in Germany and the same will likely be true in the Federal Circuit.

- Toshiko Takenaka

1Warner-Jenkinson Co. Inc., v. Hilton Davis Chemical Co. 117 S. Ct. 1040, 41 U.S.P. 1865 (1997).
2Toshiko Takenaka, Current Developments: United States, CASRIP Newsletter 5 (CASRIP, U. Wash. Seattle WA) Fall 1996 at 5.
3Robert P. Merges, Patent Law and Policy, 676 (1992).
4Graver Tank & MFG. Co. v. Linde Air Products Co. 339 U.S. 605 at_(1950).
5Perkin-Elmer Corp. v. Westinghouse Elec. Corp., 822 F.2d, at 1533, 3 U.S.P.Q.2d at 1325.
6Corning Glass Works v. Sumitomo Electoric U.S.A. Inc. 868 F.2d 1251, 9 U.S.P.Q.2d 1962 (Fed. Cir. 1989).
7Protocol on the Interpretation of Article 69 of the Convention, reprinted in Singer: The European Patent Convention 252 (1995).
Article 69 should not be interpreted in the sense that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being em ployed only for the purpose of resolving an ambiguity found in the claims. Neither should it be interpreted in the sense that the cliams serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the de scription and drawings by a person skilled in the art, the patentee comtemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for teh patentee with a reasonable degree of certain ty for third parties.
(The protocol shall be an integral part of the Convention pursuant to Article 164, paragraph 1.)

8Jochen Pagenberg, The Scope of Article 69 Euroepan Patent Convention: Should Sub-Combinations be Protected? A Comparative Analysis on the Basis of French and German Law, 24 IIC 313 (1993), reprited in Chisum etc, International Perspectives on the Legal Interpretaion of Patent Claims, CASRIP Symposium Publication Series, No. 1, 163 (1995).
9Toshiko Takenaka, Doctrine of Equivalents after Hilton Daivs, 22 Rutgers Computer and Technology Law Journal 475, 511 (1996)
10Wilson Sporting Goods Co. v. David Geoffrey & Assc. 904 F.2d 677, 14 U.S.P.Q.2d 1161 (Fed. Cir. 1990).
11Harold Wegner, The Doctrine of Equivalents after Warner Jenkinson .
12Toshiko Takenaka, New Policy in Interpreting Japanese Patents: Osaka High Court Affirms Infringement of Genetech's t-PA Patents under the Doctrine of Equivalents, CASRIP Newsletter (CASRIP, U. Wash. Seattle WA) Spring/Summer) 1996.
13Supra note 10.
14Supra note 2, Current Developments at 5.
15Toshiko Takenaka, Interpreting Patent Claims: The United States, Germany and Japan, 17 IIC Studies 261 (1995).

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