Addressing the issue of whether arguments limiting claim scope during prosecution of a parent application limit the scope of claims in a continuation, the U.S. Court of Appeals for the Federal Circuit upheld a decision that limited patent claims issued in a continuation application to the same scope as claims allowed in the parent application. Hakim v. Cannon Avent Group, PLC, Case No. 05-1398 (Fed. Cir., Feb. 23, 2007) (Newman, J.).

Hakim sued Cannon Avent Group for infringement of two his patents on spill-proof drinking cups. The district court granted Cannon summary judgment of non-infringement on the first patent. During prosecution of this patent, Hakim distinguished his invention from the prior art by emphasizing that his invention included a diaphragm with a “slit” that opens and closes. After receiving a notice of allowance, Hakim abandoned the original application in favor of a continuation which substituted the word “opening” for “slit” in the claims. The continuation claims were allowed without comment from the examiner. Cannon’s accused products had a diaphragm with an “opening,” but not a “slit.” Cannon thus argued that Hakim was limited by the disclaimer made during prosecution of the original application.

In affirming the grant of summary judgment, the Federal Circuit held that an applicant may not recapture claim scope that was previously disclaimed in an earlier application unless that disclaimer is rescinded. Furthermore, “the prosecution history must be sufficiently clear to inform the examiner that the previous disclaimer, and the prior art that it was made to avoid, may need to be re-visited.” Although Hakim had informed the examiner that he was broadening the claims in the continuation, he did not specifically point out that he no longer intended to be bound by the disclaimer. The Court held that merely informing the examiner that the new claims were broader was not sufficient to rescind the disclaimer.

Practice Note: Prosecutors and litigators alike should note that the scope of a patent claim will be limited by disclaimers made during prosecution of earlier, related applications unless those disclaimers are clearly rescinded during prosecution.