Marine Polymer Technologies, Inc. v. HemCon Inc.

Intervening rights with respect to reissued patents do not accrue where the accused product or activity infringes a claim that existed in the original patent and remains without substantive change after reissue.

Opinion (Lourie): HemCon Inc. (“HemCon”) appealed the judgment of the U.S. District Court of New Hampshire holding the HemCon infringed a patent assigned to Marine Polymer Technologies, Inc. (“Marine”). The patent at issue claims preparations of poly-acetylglucosamine, which has utility in various industrial, pharmaceutical, and biomedical applications. HemCon argued that specific claims of the patent changed in scope during reexamination, and that HemCon thereby acquired intervening rights in those claims. Thusly, HemCon argued the district court’s finding of infringement should be reversed. Although intervening rights originated as a defense against patents modified through reissue procedures, the doctrine had since been extended to the context of reexamination. The court held that after a patent emerges from reexamination, the Patent Act makes available absolute and equitable intervening rights to the same extent provided for reissued patents, but only with respect to amended or new claims in the reexamined patent. Although Marine’s arguments to examiner and cancellation of claims on reexamination may have affected the scope of claims for the patent at issue, the claims were not “amended or new,” within the meaning of the Patent Act provisions governing intervening rights. Because there were no formal changes to the actual language of the claim on reexamination, the claim was not amended or new, and the decision of the district court was AFFIRMED.