## Facts

- Cuno Incorporated and Pall-related entities were major competitors in the market for microporous nylon membrane filters.
- Cuno sued Pall in federal court alleging infringement of several U.S. patents covering membrane filters and a related production process.
- While the U.S. case was pending, Pall sued Cuno in a U.K. patent court on a European patent that was a counterpart to a Pall U.S. patent involved in the U.S. litigation; the inventions and claim language were materially similar.
- The U.K. court held Pall’s European patent valid and not infringed, making detailed fact findings and construing key claim terms.
- Pall moved for partial summary judgment in the U.S. action, arguing that the U.K. court’s claim constructions and findings should bind Cuno through collateral estoppel (issue preclusion).

## Issues

1. Whether a foreign court’s fact findings and claim constructions in litigation over a counterpart foreign patent can have collateral estoppel effect in U.S. patent litigation involving a related U.S. patent.
2. Whether differences between U.S. patent law and foreign patent regimes defeat the “identity of issues” requirement for issue preclusion and raise fairness and policy concerns sufficient to deny estoppel.

## Decision

- The court denied Pall’s motion for partial summary judgment.
- The court held that the U.K. court’s claim constructions and factual findings were not entitled to collateral estoppel effect in the U.S. proceeding.
- Because estoppel was Pall’s sole ground for partial summary judgment, the failure of estoppel required denial of the motion.

## Legal Principles

- Issue preclusion requires, among other things, that the identical issue was actually litigated and necessarily decided, the determination was essential to the judgment, the party to be bound had a full and fair opportunity to litigate, and no overriding fairness or public policy concerns counsel against preclusion.
- Patent rights are territorial; counterpart patents arise under different statutory schemes, and differences in patentability standards and interpretive methods can prevent foreign determinations from being “identical” to U.S. issues.
- Claim construction is a legal determination tied to the governing jurisdiction’s statute and interpretive methodology; a foreign court’s construction of materially similar claim language does not automatically decide the same issue under U.S. law.
- Even where parties vigorously litigate abroad, structural differences in substantive law and policy objectives may make it unfair and inconsistent with U.S. patent policy to treat foreign determinations as binding in U.S. patent litigation.

## Conclusion

The court refused to give issue-preclusive effect to a U.K. patent judgment interpreting and applying a European counterpart patent, concluding that differences in governing law and policy defeated identity of issues and raised fairness concerns; partial summary judgment based solely on collateral estoppel was therefore denied, and the U.S. patent case proceeded on the merits.


Cuno Inc. v. Pall Corp., 729 F. Supp. 234 (E.D.N.Y. 1989)