Gevo, Inc. v. Butamax Advanced Biofuels LLC

The doctrine of ensnarement will prevent a party from arguing infringement under the doctrine of equivalents when the broader coverage used to show infringement would bring prior art within the coverage of the patent.

Opinion (Robinson): Butamax Advanced Biofuels, LLC ("Butamax") sued Gevo, Inc. ("Gevo") alleging infringement of two of its patents. Gevo counterclaimed, alleging Butamax infringed two of its patents (Nos. 8,017,375 and 8,017,376), which relate to the production of isobutanol using microorganisms. The '375 patent covers the use of yeast to produce isobutanol through a five step process using Lactococcus lactis (L. lactis) yeast in the second step. The '376 patent covers a yeast with certain overexpressed polynucletides. Butamax moved for summary judgment of non-infringement. To literally infringe a patent, the accused product must implement each step of the allegedly infringed patent. If a product is not literally infringing, it may still infringe a patent under the doctrine of equivalents (DOE) if it is the functional equivalent of the claimed invention. However, if the patentee was forced to forego broader language in order to obtain a patent, it will be estopped from asserting the coverage of the broader language. Additionally, if broader coverage under the DOE would bring prior art within the coverage of the patent, the doctrine of ensnarement will preclude a finding of infringement. Because Butamax used Listeria grayi in the second step of its five step process, the court held that it did not literally infringe the '375 patent. Gevo was also estopped from arguing infringement under the DOE because it was forced to narrow the language of its claim to require use of L. lactis. Additionally, the court held that permitting the '375 patent to cover other yeast strains would violate the doctrine of ensnarement because it would bring prior art within the coverage of that patent. The court held that Butamax DID NOT INFRINGE the '376 patent because rather than overexpressing the polynucletides, Butamax's strain deleted certain genes to achieve a similar result. The court held that the deletion could not be considered the functional equivalent of the overexpression because to so hold would render the overexpression claim in the '376 patent superfluous.