Devoted to Corporate Attorneys, Corporate Lawyers, and Corporate Counsel

The following is not meant to be legal advice.

On July 5, 2007, the Federal Circuit issued a decision in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. (No. 05-1492), addressing the scope of prosecution history estoppel and its limits on the doctrine of equivalents.  Prosecution history estoppel is a legal limitation on the doctrine of equivalents.  Prosecution history estoppel prevents a patent holder from claiming subject matter surrendered during prosecution of the patent. The Festo decision addressed whether an equivalent is foreseeable and thus subject to surrender.

The Federal Circuit held a broad view of foreseeability; citing from the case: an alternative is foreseeable if one skilled in the art would have known that the alternative existed in the field of art as defined by the original claim scope, even if the suitability of the alternative for the particular purposes defined by the amended claim scope were unknown.