“a cooked dough product having a light, flaky, crispy texture”: Example of the patent process

For those curious about the actual patent process, Chef America, Inc. v. Lamb-Weston, Inc. is an interesting and short recent case. This is a typical example of how patent attorneys describe reality and how federal judges handle patent disputes.

The case concerns U.S. Pat. No. 4,761,290 (PDF version; USPTO version), owned by plaintiff Chef America.

The patent covers “[a] process for producing a dough product which is convertible upon finish cooking by baking or exposure to microwaves in the presence of a microwave susceptor into a cooked dough product having a light, flaky, crispy texture.” The patent explains that with prior dough products “[i]n large measure, instead of the desired light, flaky, crispy texture, the cooked products have been found to be leathery, in the case of baked products, or soggy in the case of microwave heated products.” It involves the process of “applying a layer of shortening flakes between the dough and a light batter which is applied to the dough, setting the batter and subsequently melting the shortening flakes present in the set batter in order to form pin holes or air cells in the batter and at the surface of the dough. Upon finish cooking, these pinholes or air cells form a porous product and permit the batter to be quickly heated and browned, resulting in a dough product having a light, flaky, crispy texture to the pocket.”The patent’s technical description explains that the dough is cooked in an oven, at a temperature from about 400 degrees F. to 850 degrees F. The problem is that the claims of the patent–which specify what invention is legally protected–include the step: “heating the resulting batter-coated dough to a temperature in the range of about 400° F. to 850° F. for a period of time ranging from about 10 seconds to 5 minutes to first set said batter and then subsequently melt said shortening flakes, whereby air cells are formed in said batter and the surface of said dough”.

The claim should have said heating the dough “at” that temperature, not “to” that temperature. The dough is in an oven which is at 400° F. to 850° F., but the dough does not reach this temperature. If it did, it would burn up. Lamb-Weston was accused of infringing the claims of Chef America’s patent. But Lamb-Weston pointed out that it did not heat dough “to 400° F.”; therefore, it did not infringe the claims.

Chef America argued “that ‘to’ should be construed to mean ‘at’ because otherwise the patented process could not perform the function the patentees intended”. In other words, the claim is nonsensical if you construe “to” to mean “to”; anyone skilled in the art (e.g., a chef) reading the claim would understand it to mean that the oven is at the specified temperature, not the dough being cooked.

However, the appeals court held that the language was unambiguous and the court would not rewrite it. As the court stated, “we construe the claim as written, not as the patentees wish they had written it. As written, the claim unambiguously requires that the dough be heated to a temperature range of 400° F. to 850° F.”

This was the correct ruling, IMHO.