Issue 163 | February 25, 2004
Chef America, Inc., v. Lamb-Weston, Inc.


Patent Claim Construction—A patent claim requiring heating of dough "to" 400 to 850 degrees F. was not construed to require heating of the dough "at" 400 to 850 degrees F. (i.e. in an oven heated to 400 to 850 degrees F.), even though the latter construction was what the patentee intended and was necessary to avoid ruining the dough. The claim language was unambiguous, and not specially defined in the specification, so it was interpreted to have its ordinary meaning

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The Federal Circuit affirmed the claim construction below, as well as the resulting summary judgment of noninfringement of the patent in suit.

The Chef America '290 patent covers a process for producing a dough product having a light, flaky, crispy texture. The relevant claims of the patent require heating the dough to a temperature in the range of about 400 to 850 degrees F.

Following a Markman claim-construction hearing, the district court granted Lamb-Weston a partial summary judgment construing the heating limitation in Claim 1 to require that the dough be heated to the specified temperature range.

The district court noted that the claims are unambiguous as written, and concluded that the claims clearly refer to the temperature of the dough, not the oven setting. The problem is that if the dough were heated to a temperature range of 400 to 850 degrees F., as the claim instructs, it would be burned to a crisp. The resulting product would resemble a charcoal briquette.

The district court subsequently granted a motion for summary judgment of non-infringement of the '290 patent. Lamb-Weston does not heat its dough products to the temperature range specified in the '290 patent and, therefore, does not literally infringe the claims as construed by the district court.

The Federal Circuit affirmed.

Courts may not redraft claims, whether to make them operable or to sustain their validity. Where as here, claims are susceptible to only one reasonable interpretation and that interpretation results in a nonsensical construction of the claim as a whole, the claim must be invalidated.

Moreover, the prosecution history suggests that the patentees intentionally used "to" rather than "at" in drafting the temperature requirements of the claim. In formulating the amendment to the claims to specify the temperature limitation, the patentees had two models before them: the heating "to" limitation of the specification and original Claim 6 and the heating "at" limitation of a working example in the specification. They chose the "to" limitation which plainly and unequivocally refers to the temperature to which the dough and not the air in the oven will be heated. It thus appears that the patentees consciously selected "to" rather than "at." There is nothing to indicate that in doing so they intended "to" to mean "at."

Chef America cited a declaration of its baking expert, Mr. Lehmann, that the claim requires placing the dough in an oven set to a temperature in the range of about 400 to 850 degrees F. The Lehmann declaration shows that he read the claim in accordance with the construction proffered by plaintiff, not because the words had special meaning to him, but because it is well known that raising the temperature of a dough product itself to such high temperatures would result in an unusable product. Mr. Lehmann did not explain how the word "to" in the claim could be read to mean "at" or even state that persons of ordinary skill in the baking art would so do. Therefore, this declaration did not change the result.

Please e-mail George Wheeler of McAndrews, Held & Malloy, Ltd. at gwheeler@mhmlaw.com with any questions that you might have about this case.

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