## Facts

- Chef America, Inc. owned U.S. Patent No. 4,761,290, which claimed a process for producing a dough product with a light, flaky, crispy texture after final cooking.
- Claim 1 included a step requiring “heating the resulting batter-coated dough to a temperature in the range of about 400° F. to 850° F.”
- Chef America argued the temperature range referred to the oven temperature, because heating the dough itself to 400–850°F would burn it; it urged construing “to” as effectively meaning “at.”
- Lamb-Weston, Inc. argued the claim language required the dough itself to reach the stated temperatures and asserted its process did not heat dough to that internal range.
- The district court construed the limitation to require heating the dough itself to 400–850°F and granted summary judgment of noninfringement to Lamb-Weston.

## Issues

1. Whether the claim phrase “heating the resulting batter-coated dough to a temperature in the range of about 400° F. to 850° F.” requires the dough itself to reach that temperature range or merely specifies the temperature of the heating environment (e.g., an oven).

## Decision

- The Federal Circuit affirmed the district court’s claim construction and summary judgment of noninfringement.
- The court held the claim unambiguously requires heating the batter-coated dough itself “to” 400–850°F, not heating it “at” an oven temperature in that range.
- Because Lamb-Weston did not perform a process in which the dough itself reached 400–850°F, it did not infringe.

## Legal Principles

- Claim construction begins with the ordinary meaning of claim language; common words are given their ordinary English meaning absent proof of specialized usage in the art.
- Courts do not rewrite clear claim language to match asserted intent, commercial practicality, operability, or to avoid seemingly nonsensical results.
- The specification and extrinsic evidence cannot override unambiguous claim text; expert testimony about feasibility does not establish a special meaning for otherwise clear words.
- Where a limitation plainly states a target temperature the material is heated “to,” the limitation is read as requiring the material itself to reach that temperature.

## Conclusion

The Federal Circuit enforced the claim’s plain wording, refused to substitute “at” for “to,” and affirmed noninfringement because the accused process did not heat the dough itself to the claimed 400–850°F range.


Chef Am., Inc. v. Lamb-Weston, Inc., 358 F.3d 1371 (Fed. Cir. 2004)