A person can infringe a patent under the doctrine of equivalents (“DOE”) which may be limited by prosecution history estoppel (“PHE”). The Supreme Court in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), finalized the basic doctrine of PHE in the context of claim amendment. A narrowing amendment of a claim results in a presumption that a patentee has surrendered the scope between the original claim and amended claim, but the patentee is allowed to rebut the presumption by proving any of three exceptions. Among those exceptions is the “unforeseeable” exception under which a patentee may show that the alleged equivalent was unforeseeable at the time of amendment. This article found that the Federal Circuit case law has transformed the “unforeseeable” exception into “foreseeability” estoppel which may completely bar the application of DOE.
- Doctrine of Equivalents,
- Prosecution History Estoppel,
- Patent Infringement,
- Claim Amendment,
Available at: http://works.bepress.com/ping-hsun_chen/1/