Definition
Prosecution history estoppel prevents a patent owner from claiming, through the doctrine of equivalents, subject matter that was surrendered by amendment or argument during prosecution.
Why It Matters Legally
This doctrine can sharply limit the reach of a patent in litigation, so every amendment and argument made during prosecution has lasting consequences. It is a major reason prosecution must be handled carefully.
Example Use Case
Because the applicant narrowed a claim during prosecution, the court bars it from later arguing the competitor’s slightly different product is equivalent.
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Related Terms
Claim Amendment, Doctrine of Equivalents, Patent Prosecution, Claim Construction, Patent Litigation