In reversing and vacating a district court’s decision to grant injunction and reasonable royalty damages for patent infringement, the U.S. Court of Appeals for the Federal Circuit held that intervening rights can apply to an original claim based on arguments made by the patentee during reexamination.   Marine Polymer Technologies, Inc. v. HemCon, Inc., Case No. 10-1548 (Fed. Cir., Sept. 26, 2011) (Dyk, J.) (Lourie, J., dissenting).  Intervening rights typically occur where the scope of coverage of a patent changes during reexamination.

Marine Polymer sued HemCon for infringing its patent claiming a biocompatible polymer.   In the ensuing litigation, the district court construed the term “biocompatible” as meaning polymers “with no detectable biological reactivity as determined by biocompatibility tests.”  Meanwhile, in the parallel reexamination proceeding, the examiner construed the term “biocompatible” as meaning polymers with “little or no detectable reactivity” reasoning that certain dependent claims recited a biocompatibility test score that is greater than zero.  Marine Polymer urged the examiner to adopt the district court’s claim construction and canceled all dependent claims reciting a biocompatibility test score greater than zero.  In view of the cancellation of those dependent claims, the examiner adopted the district court’s claim construction, and the remaining claims were issued.

In this appeal from the district court (where HemCon was subjected to a $29 million dollar damages award against it), HemCon argued that it was entitled to intervening rights because Marine Polymer changed the scope of the claims of the asserted patent during reexamination.  Marine Polymer, contended that intervening rights cannot apply because the actual language of the asserted claims was not amended during reexamination.

The Federal Circuit agreed with HemCon and held that Marine Polymer indeed narrowed the scope of the claims by “argument rather than changing the language of the claims to preserve otherwise invalid claims.”   Noting that intervening rights are available if the original claims have been “substantively changed,” the Court emphasized that “in determining whether substantive changes have been made, we must discern whether the scope of the claims [has changed], not merely whether different words are used.”  In particular, those dependent claims that were canceled during reexamination indicated that “the term ‘biocompatible’ must include slight or mild biological reactivity.”  As such, the district court’s claim construction, which required that the polymer show “no detectable biological reactivity,” imposed a new claim limitation that narrowed the scope of the claims. Therefore, intervening rights did apply in this case, as “argument to PTO on reexamination constituted disavowal of claim scope even though ‘no amendments were made.’”

Judge Lourie dissented and argued that the majority went beyond the statutory rules for intervening rights under 35 U.S.C. §§ 307(b) and 316(b).   Judge Lourie believes that, according to the language of the statute, intervening rights should only apply to “amended or new claims.”

Practice Note:   Post-grant proceedings could be a pitfall for patentees seeking to enforce their patents.  A patentee should consider whether it would be better off filing a continuing application before grant of the original patent to leave a vehicle to present new or amended claims.