## Facts

- Marine Polymer Technologies, Inc. owned U.S. Patent No. 6,864,245 covering “biocompatible” p‑GlcNAc compositions used to accelerate hemostasis.
- Marine Polymer sued HemCon, Inc. for patent infringement in the District of New Hampshire.
- The parties disputed the meaning of “biocompatible”; the district court adopted a construction tied to the patent’s disclosed tests and limited the term to materials producing at most slight or no adverse biological response.
- Under that construction, the district court granted summary judgment of literal infringement on seven claims; a jury awarded damages, and the court issued injunctive relief.
- While the case was pending, HemCon sought ex parte reexamination, urging a broader view of “biocompatible” supported by certain dependent claims.
- The PTO examiner initially rejected all claims using a construction differing from the district court’s, citing a conflict between the district court’s construction and dependent-claim language.
- In reexamination, Marine Polymer canceled the dependent claims that the examiner viewed as inconsistent and argued for the district court’s narrower construction; the text of the asserted independent claims was not amended.
- The examiner then allowed the remaining claims under the narrower construction.
- A Federal Circuit panel initially held the reexamination effectively changed claim scope and conferred intervening rights on HemCon, vacating damages and injunctive relief.
- The Federal Circuit reheard the case en banc and vacated the panel decision.

## Issues

1. Whether intervening rights under 35 U.S.C. §§ 252 and 307(b) can arise in reexamination when the asserted claim language is unchanged, but the patentee cancels other claims and makes arguments that result in a different claim construction at the PTO.
2. Whether the district court’s infringement judgment and remedies could be displaced based on intervening rights stemming from the reexamination.

## Decision

- The en banc court held intervening rights did not apply because the asserted claims were neither amended nor newly added during reexamination.
- The court rejected treating cancellations of other claims and argument-driven shifts in claim construction as “amendments” for purposes of §§ 252 and 307(b).
- The panel’s intervening-rights ruling was reversed, leaving the district court’s infringement judgment in place.
- The court affirmed the district court’s infringement judgment by an equally divided court.

## Legal Principles

- Intervening rights under 35 U.S.C. § 252, as incorporated into reexamination by § 307(b), attach only to “amended or new” claims.
- Whether a claim is “amended” for intervening-rights purposes turns on changes to the claim’s actual text, not on prosecution arguments or cancellation of other claims.
- Narrowing or clarifying claim scope through reexamination arguments—without changing the asserted claim language—does not, by itself, create absolute or equitable intervening rights.

## Conclusion

The Federal Circuit held that intervening rights in reexamination require an actual textual amendment to an asserted claim or the addition of a new claim; cancellations of other claims and argument-based claim-construction outcomes do not trigger intervening rights, so the accused infringer could not avoid liability on that basis.


Marine Polymer Techs., Inc. v. HemCon, Inc., 672 F.3d 1350 (Fed. Cir. 2012) (en banc)