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Dependent claim can be construed to be broader than independent claim based on prosecution history

By McKee, Voorhees & Sease, P.L.C.

In a decision last week, the Federal Circuit held a district court construed 1 of 2 claim terms correctly, and incorrectly concluded that prosecution history estoppel barred application of the doctrine of equivalents to a third claim term because the narrowing amendment was only tangentially related to the equivalent at issue.  As a result, the court affirmed in part, reversed in part, and remanded.

One of the claim construction issues was interesting in that the court held that the prosecution history of the patent overcame the "presumption" of claim differentiation, namely that "dependent claims are presumed to be of narrower scope than the independent claims from which they depend."  This led to the strange result that the scope of some dependent claims was outside the scope of the independent claim from which they depended.  This seems to be contrary to § 112 ¶ 4, which requires a dependent claim "shall be construed to incorporate by reference all the limitations of the claim to which it refers."

Judge Prost dissented from the portion of the ruling regarding prosecution history estoppel, and would have held that the amendment was not tangential to the equivalent in question and therefore that prosecution history estoppel applied.

More detail of Regents of the U. of Cal. v. Dakocytomation Cal., Inc. after the jump.

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Full post as published by FileWrapper on March 03, 2008 (boomark / email).