Prosecution history estoppel

The basic effect of the doctrine of equivalents is to allow the patent owner to expand the scope of protection afforded by the literal language of the claims. However, the doctrine of equivalents does not allow the patent owner to expand the scope of the claims without restriction. The ability of the patent owner to expand the scope of the patent claims is restrained by the prior art and also by the doctrine of prosecution history estoppel. 

The doctrine of prosecution history estoppel also limits the degree to which the claims may be interpreted under the doctrine of equivalents. The doctrine of prosecution history estoppel precludes the patent owner from interpreting the claims in a manner that would encompass, within the claim, subject matter that the patent owner surrendered during prosecution of the patent application to achieve issuance of the patent. Any subject matter that the patent owner surrendered during prosecution to obtain allowance of claims made in the application of the patent cannot be reclaimed under the doctrine of equivalents. 

Additional guidelines, relating to the doctrine of equivalents and the rule of prosecution history estoppel, and based on the Supreme Court decisions in the cases of Festo Corporation v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 122 S.Ct. 1831 (2002) and Warner Jenkinson Company, Inc., v. Hilton Davis Chemical Co., 117 S.Ct. 1040 (1997), shed light on the limits and requirements of a finding of infringement under the doctrine of equivalents, as follows ... 

Prosecution history estoppel requires that claims of a patent be interpreted in hght of proceedings in patent office during the prosecution process,... 

Prosecution history estoppel may apply to any claim amendment made to satisfy a statutory requirement of the patent act,... 

A patentee alleging inflingement under the doctrine of equivalents can rebut the presumption that the prosecution history estoppel bars a finding of equivalence by showing that at the time of amendment one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent, and... 

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