Patent Case Watch

Patent opinions from the Eastern District of Texas and the U.S. Court of Appeals for the Federal Circuit

Weekly Digest

Doctrine of Equivalents

The doctrine of equivalents allows a finding of infringement where an accused product does not literally meet a claim limitation but differs from it only insubstantially - often framed as performing substantially the same function in substantially the same way to achieve substantially the same result. The comparison is made limitation by limitation rather than to the invention as a whole. Several doctrines constrain it: prosecution history estoppel bars recapturing subject matter surrendered during prosecution, and the claim vitiation and disclosure-dedication rules prevent it from erasing a limitation entirely. The opinions here address when the doctrine is available and what evidence supports an equivalents theory.

109 opinions and orders.