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On Remand Federal Circuit Clarifies Issues Concerning Prosecution History Estoppel

September 26, 2003

Decision icon Decision, en banc

Last Month at the Federal Circuit - October 2003

Judges: Lourie (author), Rader (concurring), and Newman and Mayer (concurring-in-part and dissenting-in-part) (en banc)

In Festo Corporation v. Shoketsu Kinzoku Kogyo Kabushiki Co., No. 95-1066 (Fed. Cir. Sept. 26, 2003), the Federal Circuit, on remand from the Supreme Court, provided significant guidance to patent practitioners on the application of prosecution history estoppel and the DOE, and remanded the case to the district court for further determination of whether Festo Corporation (“Festo”) can rebut the presumption of surrender by establishing that the equivalence in question would have been unforeseeable to one of ordinary skill in the art at the time of the amendments in question.

The Federal Circuit explained that the presumptions set forth by the Supreme Court in Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997), and Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 533 U.S. 1915 (2001), operate together to control the prosecution history estoppel inquiry. The Court explained that the first question in the inquiry is whether an amendment filed in the PTO has narrowed the literal scope of a claim. If the amendment was not narrowing, then prosecution history estoppel does not apply. But, if the amendment was a narrowing one, then the second question is whether the reason for that amendment was a substantial one relating to patentability.

When the prosecution history record reveals no reason for a narrowing amendment, then Warner- Jenkinson presumes that the patentee had a substantial reason relating to patentability; consequently, the patentee must show that the reason for the amendment was not one relating to patentability if it is to rebut that presumption. In this regard, the Federal Circuit reinstated its earlier holding that a patentee’s rebuttal of the Warner-Jenkinson presumption is restricted to the evidence in the prosecution history record. If the patentee successfully establishes that the amendment was not for a reason of patentability, then prosecution history estoppel does not apply.

If it is determined that a narrowing amendment has been made for a substantial reason relating to patentability, then the next step in the analysis is to determine the scope of the subject matter surrendered by the narrowing amendment. Here, the patentee may rebut the presumption of total surrender imposed by the Supreme Court in Festo by demonstrating that the alleged equivalent would have been unforeseeable at the time of the narrowing amendment, that the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent in question, or that there was some other reason suggesting that the patentee could not reasonably be expected to have described the alleged equivalent.

The Federal Circuit also ruled that the question of whether the presumption of surrender has been rebutted is one of law to be determined by the Court, not a jury. However, in determining whether an alleged equivalent would have been unforeseeable, a district court may hear expert testimony and consider other extrinsic evidence relating to the relevant underlying factual inquiries. If the patentee is attempting to establish a merely tangential reason for a narrowing amendment, the Court must make this determination from the prosecution history record only, without the introduction of additional evidence, except for, when necessary, testimony as to the interpretation of that record. The Court left for another day the question of whether evidence outside the prosecution history record should be considered in determining if a patentee has met his burden under the third rebuttal criterion, indicating, however, that when at all possible, determination of the third rebuttal criterion should also be limited to the prosecution history record.

Finally, the Court clarified that the time when the narrowing amendment was made, and not the filing date of the application, is the relevant time for evaluating unforeseeability.

Applying this analysis to the facts of this case, the Federal Circuit determined that factual issues exist relating to the objective unforeseeability of the accused equivalents and remanded the case for further consideration of that issue. The Federal Circuit also ruled that Festo could not satisfy the third rebuttal criterion for certain amendments made and was estopped from arguing that certain other amendments were “tangential” or made for “some other reason.”

Judge Newman, joined by Judge Mayer, dissented with that portion of the opinion that precludes Festo from attempting to overcome the presumption of surrender with regard to certain claim limitations and with that portion of the opinion regarding the factual criteria of ”tangentialness” and “other reasons” as a question of law, and with the adjudication of these issues without the procedures of trial.