## Facts

- Takeda owned U.S. Patent No. 6,328,994 covering an orally disintegrable lansoprazole tablet formulation marketed as Prevacid SoluTab.
- The patent’s objective was to use granules small enough to avoid a rough feeling in the mouth when the tablet disintegrates.
- The appeal ultimately concerned claim 1, which required “fine granules having an average particle diameter of 400 µm or less.”
- Zydus filed an ANDA seeking approval to market a generic version and was sued under the Hatch-Waxman Act.
- Zydus’s ANDA product had an average particle diameter of about 412.28 µm.
- Takeda argued that particle-size measurement involves inherent error and that a ±10% margin should be treated as implicit in the claim, bringing Zydus’s product within the claim.
- Zydus argued the limitation was a strict numerical upper bound: no more than 400 µm.
- The district court construed the limitation to include the asserted ±10% tolerance, found infringement, and rejected Zydus’s invalidity defenses.
- Zydus appealed the claim construction, infringement finding, and the rejection of invalidity defenses.

## Issues

1. Whether “average particle diameter of 400 µm or less” should be construed as a strict numerical limit or as including an implicit ±10% measurement tolerance.
2. Whether Zydus proved claim 1 invalid (including for lack of written description, lack of enablement, or obviousness) by clear and convincing evidence.

## Decision

- The Federal Circuit reversed the district court’s claim construction to the extent it incorporated a ±10% tolerance not stated in the claim or supported by intrinsic evidence.
- Under the proper construction, Zydus’s ANDA product (average particle diameter ~412.28 µm) did not infringe claim 1; the infringement judgment was reversed.
- The Federal Circuit affirmed the district court’s determination that Zydus failed to prove claim 1 invalid; the no-invalidity judgment was affirmed.
- Disposition: reversed as to infringement; affirmed as to validity.

## Legal Principles

- Clear numerical claim limits are generally given their ordinary meaning and should not be expanded by extrinsic testimony absent strong intrinsic support.
- Courts may not rewrite a claim to add a measurement tolerance when the patent’s claim language, specification, and prosecution history do not define or require such a margin.
- General evidence that measurements have uncertainty does not, by itself, change the legal boundary set by a numerical claim limitation.
- Patents are presumed valid; an accused infringer bears the burden to prove invalidity by clear and convincing evidence.

## Conclusion

The Federal Circuit held that the patent’s “400 µm or less” limitation set a strict maximum average granule size and could not be broadened by an implied ±10% measurement tolerance, leading to reversal of infringement, while separately affirming that the claim was not proven invalid.


Takeda Pharmaceutical Co. v. Zydus Pharmaceuticals USA, Inc., 743 F.3d 1359 (Fed. Cir. 2014)