Article by Tom Irving, Esther H. Lim, and Jeffrey H. Tidwell
Originally published in Intellectual Property Today, December 2002
Introduction
On May 28, 2002, the U.S. Supreme Court rendered a decision highly anticipated by members of the patent bar, a decision that could impact thousands of issued patents. The ruling in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. ___, 122 S. Ct. ___ (2002), was whether prosecution history estoppel would prevent patentees from asserting infringement under the doctrine of equivalents. Significantly, the Supreme Court rejected the Federal Circuit’s en banc decision that a patentee is not entitled to any scope of equivalents for patent claims narrowed by amendment for reasons related to patentability. Instead, the Court reaffirmed the viability of the doctrine of equivalents and reinstated a flexible-bar approach. The Supreme Court, however, agreed with the Federal Circuit that a presumption of estoppel applies when a claim is
