By Gary R. Maze of Berenbaum Weinsheink PC and Richard T. Redano of Richard T. Redano, P.C.1
A narrowing dependent claim which excludes a limitation of any claim from which it depends or fails to specify a further limitation of the subject matter claimed in the claim(s) from which it depends is invalid under 35 U.S.C. §112 ¶ 4. Whether a dependent claim violates 35 U.S.C. §112 ¶¶ 3-4 is an issue rarely litigated. Accordingly, a paucity of Federal Circuit jurisprudence exists addressing this issue. This paper explores common examples of dependent claims that run afoul of Section 112 ¶¶ 3-4.
A. Long Held Precedent Defines Certain Patent Claim Language Terms
Many times, a patentee will accuse an alleged infringer of infringing, inter alia, one or more dependent claims of the patent in suit. Under Federal Circuit precedent,
One may infringe an independent claim and not infringe a claim dependent on that claim. The reverse is not true. One who does not infringe an independent claim cannot infringe a claim dependent on (and thus containing all the limitations of) that [independent] claim.2
Infringement most often turns on how the terms in the asserted claims’ limitations are construed by the court during claim construction.
A brief review of some established rules of patent claim construction is helpful. Claim l...