## Facts

- Roper owned U.S. Patent No. 4,028,520, directed to a “common-cavity” domestic oven combining conventional thermal cooking, microwave cooking, and pyrolytic self-cleaning.
- The three operating modes imposed conflicting design requirements: thermal cooking favored limited airflow; microwave cooking required strong cavity sealing and active vapor exhaust; pyrolytic cleaning risked “autoignition” that could force smoke and debris back through the waveguide and foul it.
- Under Torrey’s direction, Roper developed an airflow/venting arrangement that allowed the three modes to operate without waveguide fouling.
- The patent’s disclosure attributed prevention of waveguide fouling during occasional autoignition to continued convection cooling of the magnetron/waveguide.
- Raytheon sought a declaratory judgment of invalidity and noninfringement; Roper counterclaimed for infringement.
- After trial, the district court held the patent invalid for lack of utility and nonenablement based on findings that the asserted convection during autoignition did not occur, but also found the invention nonobvious and infringed and denied Raytheon attorney fees.
- Roper appealed the invalidity ruling; Raytheon cross-appealed the nonobviousness, infringement, and fee rulings.

## Issues

1. Whether a patent lacks utility under 35 U.S.C. § 101 because a described functional advantage or theory of operation (convection during autoignition) is inaccurate.
2. Whether a disclosure is nonenabling under 35 U.S.C. § 112 when it may explain the invention’s operation incorrectly, despite the invention being buildable and operable.
3. Whether it was error to invalidate an entire patent where the disputed limitation was recited, if at all, only in particular claims.
4. Whether the findings of nonobviousness and infringement should be reversed, and whether denial of attorney fees was improper.

## Decision

- The Federal Circuit reversed the judgment invalidating the patent in its entirety for lack of utility and nonenablement.
- The court held that the district court improperly treated a disputed operational explanation as dispositive of utility and enablement and failed to apply a proper claim-by-claim analysis.
- The court affirmed the district court’s findings of nonobviousness and infringement.
- The court affirmed the denial of attorney fees on the existing record and remanded for further proceedings consistent with its validity rulings.

## Legal Principles

- Utility under § 101 is satisfied if the invention as claimed has identifiable, practical usefulness; a patent is not invalid merely because every stated advantage in the specification is not realized as described.
- Utility should not be equated with the patentee’s theory of operation; incorrect explanation of why a device works does not, by itself, show lack of utility.
- Enablement under § 112 focuses on whether the disclosure teaches a person skilled in the art to make and use the claimed invention; an erroneous or incomplete scientific explanation does not defeat enablement if the invention can be practiced.
- Validity must be assessed on a claim-by-claim basis; alleged deficiencies tied to a particular limitation do not justify invalidating claims that do not include that limitation.

## Conclusion

The Federal Circuit held that a working, teachable invention is not rendered invalid for lack of utility or enablement solely because the specification contains an incorrect operational explanation, and it required claim-specific analysis rather than blanket invalidation, while leaving undisturbed the findings of nonobviousness, infringement, and no exceptional-case fees.


Raytheon Co. v. Roper Corp., 724 F.2d 951 (Fed. Cir. 1983)