LegiStorm

Summary:

On May 28, 2002, the U.S. Supreme Court handed down its unanimous decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd. , 535 U.S. ___, 122 S. Ct. 1831, 152 L. Ed. 2d 944 [hereinafter Festo ], reversing the most controversial of the holdings in the case by the U.S. Court of Appeals for the Federal Circuit (CAFC), vacating the decision, and remanding the case for further proceedings. The CAFC decision had been criticized as upsetting well-settled expectations and understandings concerning the operation of certain legal principles, namely, the doctrine of equivalents and prosecution history estoppel. The doctrine of equivalents provides that a product or process that does not literally infringe a patent can still be found to be infringing if the differences between the allegedly infringing product or process and the patented invention are minimal and insubstantial, that is, if the allegedly infringing product or process is substantially equivalent to the patented invention. The doctrine of equivalents is limited by prosecution history estoppel. Prosecution history estoppel provides that, as a patent applicant surrenders subject matter during prosecution to avoid rejection, i.e. , amends claims to narrow them for reasons related to patentability, the patentee also surrenders that subject matter for purposes of any infringement suit based on the doctrine of equivalents. For example, an applicant applies to patent a plastic-top table with metal legs. The examiner rejects the claim for metal legs because prior art includes a plastic-top table with rigid metal legs, so the applicant narrows the claim to distinguish it from prior art by amending it to cover a plastic-top table with collapsible metal legs folding into two parts; the patent is granted. The patentee cannot now claim that a plastic-top table with rigid metal legs is equivalent and should be found infringing, because the patentee surrendered rigid metal legs in the narrowing amendment. In the past the CAFC had applied a "flexible bar" rule which meant that, out of a range of possible equivalents, e.g. , a plastic-topped metal-legged table that folds differently from the patented table, prosecution history estoppel did not necessarily bar a finding of infringement under the doctrine of equivalents for the entire range. In Festo , the CAFC established a new "complete bar" rule which meant prosecution history estoppel would completely bar the application of the doctrine of equivalents. The Supreme Court reversed this holding, reinstating and affirming the "flexible bar" rule as the appropriate rule and the one more consistent with the spirit of the doctrine of equivalents. At the same time, the Court affirmed the holding of the CAFC that prosecution history estoppel applies to an amendment which narrowed claims in order to satisfy any patent requirement, rejecting the petitioner's argument that such estoppel only applies to an amendment which narrowed claims to avoid prior art. The Court remanded the case for further proceedings to decide whether the amendments made by the Festo Corporation surrendered the particular equivalents at issue in the case under the "flexible bar" rule. It noted that the concerns of those who desired a clearer, "bright line" rule with regard to estoppel and equivalents would be best directed to Congress which could alter the doctrine legislatively. In the wake of its Festo decision, on June 3, 2002, the Supreme Court granted certiorari in nine patent cases, then vacated prior rulings in those cases and remanded them for further proceedings taking into consideration the rules announced in Festo .