Federal Circuit Decides <i>Festo</i> on Remand from Supreme Court

In the Supreme Court case, Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 535 U.S. 722, 741 (2002), the Supreme Court agreed with the Federal Circuit that narrowing a claim during prosecution for patentability reasons may give rise to an estoppel barring the assertion of the doctrine of equivalents. However, the Supreme Court disagreed that this should result in a complete bar. Instead, it ruled that a narrowing amendment simply gives rise to a presumption that a patentee has surrendered all the subject matter between the original claim and the amended claim. Id. at 737-741. This presumption can be overcome by showing that, at the time of the amendment, one of ordinary skill in the art could not have reasonably drafted a claim that would have literally encompassed the alleged equivalent. The Supreme Court explained that a patentee could do this by showing that: 1) the equivalent was “unforeseeable” at the time of the amendment; 2) the rationale of the amendment was only “tangentially” related to the equivalent in question; or 3) there was “some other reason” for which one could not have been reasonably expected to describe the equivalent in the patent specification. Id. at 738-741.