00-1543 Festo Corp. v. Shoketsu Kinzoku Kogyokabushiki Co.

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Prosecution history estoppel does not bar the inventor from asserting infringement against every equivalent to the narrowed element. Though estoppel can bar challenges to a wide range of equivalents, its reach requires an examination of the subject matter surrendered by the narrowing amendment. The Federal Circuit’s complete bar rule is inconsistent with the purpose of applying the estoppel in the first place-to hold the inventor to the representations made during the application process and the inferences that may be reasonably drawn from the amendment. By amending the application, the inventor is deemed to concede that the patent does not extend as far as the original claim, not that the amended claim is so perfect in its description that no one could devise an equivalent.

The Court’s view is consistent with precedent and PTO practice. The Court has consistently applied the doctrine in a flexible way, considering what equivalents were surrendered during a patent’s prosecution, rather than imposing a complete bar that resorts to the very literalism the equivalents rule is designed to overcome. E.g., Goodyear Dental Vulcanite Co. v. Davis, 102 U.S. 222, 230. The Federal Circuit ignored Warner-Jenkinson ‘s instruction that courts must be cautious before adopting changes that disrupt the settled expectations of the inventing community.

See 520 U.S., at 28. Inventors who amended their claims under the previous case law had no reason to believe they were conceding all equivalents. Had they known, they might have appealed the rejection instead. Warner-Jenkinson struck the appropriate balance by placing the burden on the patentee to prove that an amendment was not made for a reason that would give rise to estoppel. Id., at 33. Similarly, the patentee should bear the burden of showing that the amendment does not surrender the particular equivalent in question. As the author of the claim language, his decision to narrow his claims through amendment may be presumed to be a general disclaimer of the territory between the original claim and the amended claim. Exhibit Supply, supra, at 136-137. However, in cases in which the amendment cannot reasonably be viewed as surrendering a particular equivalent-e.g., where the equivalent was unforeseeable at the time of the application or the rationale underlying the amendment bears but a tangential relation to the equivalent-the patentee can rebut the presumption that prosecution history estoppel bars a finding of equivalence by showing that at the time of the amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent.

234 F.3d 558, vacated and remanded.

Local effect:

The decision reverses current law in the federal circuit.

Kennedy, J.