Fletcher YoderA district court must construe all disputed claim terms when the meaning of the terms affects the scope of the claims. The doctrine of equivalents does not apply if the objectively apparent reason for a narrowing amendment is not tangential to an alleged equivalent as indicated by clear claim language.
Narrowing amendment to independent claim at issue was not inadvertent, and was made for substantial reason related to patentability, namely, to avoid prior art; prosecuting attorney’s declaration that narrowing limitation was added inadvertently cannot be considered in determining reason for amendment, since it is not part of the prosecution history, and prosecution history does not show that reason for amendment was inadvertent.