The Supremes Weigh In on Patent Law’s Doctrine of Equivalents: The Supreme Court has finally issued its Doctrine of Equivalents (“DoE”) decision in Festo (May 28, 2002). In a unanimous decision, the Court vacated the CAFC’s decision and remanded the case.
The Court, in sum, agreed with the CAFC that prosecution history estoppel can apply to any claim amendment made to satisfy the Patent Act’s requirements, not just to amendments made to avoid the prior art. However, the Court disagreed with the CAFC’s (more certain) complete bar rule, and adopted a (less certain) rebuttable presumption approach. Under this approach, amending a patent claim to satisfy a Patent Act requirement, including §112’s requirements concerning form, creates a rebuttable presumption that the amendment was intended to narrow the claim, thus giving rise to estoppel for equivalents. However, the estoppel is only presumed to apply to all equivalents; the presumption may be rebutted if the patentee can show that the amendment did not surrender the particular equivalent in question, for example by showing that the amendment involved a feature that was “unforeseeable at the time of the application” or “for some other reason” could not be included in the original claim. The rebuttable presumption rule does not curtail equivalents as much as the CAFC’s complete bar rule did, but it will still be difficult for patentees to overcome the presumption. The end result is that equivalents infringement will be harder to show than before Festo, but easier than under the CAFC’s now-defunct Festo ruling.
Other info: recent blog entries; Law.com article.
More detail.The CAFC had previously ruled, in the controversial en banc decision Festo, that prosecution history estoppel arises from any amendment that narrows a claim to comply with the Patent Act, not only from amendments made to avoid the prior art. The CAFC also held that, when estoppel applies, it bars any claim of equivalence for the element that was amended. Under its prior cases, prosecution history estoppel constituted a flexible bar, foreclosing some, but not all, claims of equivalence, depending on the purpose of the amendment and the alterations in the text. However, the CAFC overruled its precedents on the ground that their case-by-case approach had proved unworkable.
The Supreme Court held that prosecution history estoppel may apply to any claim amendment made to satisfy the Patent Act’s requirements, not just to amendments made to avoid the prior art, but estoppel need not bar suit against every equivalent to the amended claim element. The Court held that estoppel arises when an amendment is made to secure the patent and the amendment narrows the patent’s scope. If a §112 amendment is truly cosmetic, it would not narrow the patent’s scope or raise an estoppel. But if a §112 amendment is necessary and narrows the patent’s scope–even if only for better description–estoppel may apply.
However, the Court disagreed with the CAFC’s complete bar rule, as being 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 Court held, 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 DoE must be applied 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 DoE is designed to overcome. Thus, 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.
Under the new regime announced by the Court, therefore, the burden is on the patentee who amends claims, to prove that an amendment was not made for a reason that would give rise to estoppel; and to show that the amendment does not surrender the particular equivalent in question. Thus, although the patentee, as the author of the claim language, may be presumed to have made a general disclaimer of the territory between the original claim and the amended claim, this presumption may be rebutted. For example, 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.
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