## Facts

- FAS owned U.S. Patent No. 5,167,837, directed to devices and methods for accurately dispensing industrial liquids in semiconductor manufacturing.
- Cybor manufactured an accused liquid-dispensing pump (Model 5226).
- FAS sued Cybor for patent infringement in the U.S. District Court for the Northern District of California.
- The case turned largely on the meaning of disputed claim terms and whether the accused pump fell within the properly construed claims.
- A jury returned a verdict against Cybor; the district court entered judgment of infringement and denied Cybor’s renewed motion for judgment as a matter of law.
- The district court also denied FAS enhanced damages, exceptional-case status, and attorney’s fees under 35 U.S.C. § 285.
- Cybor appealed the claim construction and infringement judgment; FAS cross-appealed on damages, enhancement, and fees.
- The Federal Circuit took the case en banc to address the standard of appellate review for claim construction.

## Issues

1. What standard of appellate review applies to patent claim construction: de novo review as a purely legal issue, or deferential review for any fact-dependent components?
2. Under the correct standard, did the district court correctly construe the asserted claims and properly find Cybor’s pump infringed?
3. Did the district court err in denying enhanced damages, an exceptional-case finding, and attorney’s fees?

## Decision

- The en banc Federal Circuit held that claim construction is a question of law reviewed de novo on appeal.
- The court rejected the view that any “fact-based” components of claim construction receive deferential review under Federal Rule of Civil Procedure 52(a).
- Applying de novo review, the court agreed with the district court’s claim constructions.
- The court affirmed the judgment that Cybor’s Model 5226 pump infringed the asserted claims.
- The court affirmed the district court’s damages rulings and its denial of enhanced damages, exceptional-case status, and attorney’s fees.

## Legal Principles

- Patent infringement analysis proceeds in two steps: (1) construe the claims; (2) compare the construed claims to the accused device or process.
- Claim construction is for the court and is treated as a question of law subject to de novo appellate review.
- Use of extrinsic evidence (e.g., expert testimony and technical materials) may assist the court’s understanding of claim meaning, but does not convert claim construction into factual findings entitled to appellate deference.
- Appellate de novo review was justified as supporting nationwide uniformity in claim interpretation within the specialized patent appellate system.

## Conclusion

The Federal Circuit, sitting en banc, held that patent claim construction is reviewed de novo in all respects and affirmed the infringement judgment and related rulings, consolidating appellate control over claim meaning while rejecting trial-court deference in claim interpretation.


Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc)