Patent Owners Gain Revitalized Right of Enforcement Against Equivalents

Patent Owners Gain Revitalized Right of Enforcement Against Equivalents

 by Robert M. Asher


Recent decisions by the Federal Circuit Court of Appeals have breathed life into the doctrine of equivalents. This doctrine is judge-made law that allows patent owners to establish infringement when an accused product or method has skirted the literal wording of the patent claims but is only insubstantially different from the claimed invention.

The claims of a patent typically define the legal scope of the invention. The broader the claims, the more expansive the patent protection and the more difficult it is to get the claims allowed in the U.S. Patent and Trademark Office.

Due to the vagaries of language and invention and the unforeseeability of all variations on an inventive concept, any word or phrase in a patent claim offers aggressive competitors an opportunity to design around the words, while still benefiting from the inventive teachings. The doctrine of equivalents was developed to protect the invention when the claim language turns out to be too limiting.

The patent litigated in Deere & Co. v. Bush Hog, LLC, 2012 U.S. App. LEXIS 8527 (Fed. Cir., Apr. 25, 2012) [an enhanced version of this opinion is available to subscribers]  was directed to a rotary cutter deck that houses one or more powered mower blades. The upper deck slopes downwardly "into engagement with, and being secured to" the lower deck. Rather than directly engaging the upper deck with the lower deck, the accused products included an intermediate structure connecting the upper deck to the lower deck.

The district court judge found no infringement because the upper deck of the accused product did not directly contact the lower deck. The Federal Circuit reversed, stating "into engagement with" did not require direct contact. Indirect contact could suffice. Deere & Co. v. Bush Hog, LLC, 703 F.3d 1349 (Fed. Cir. 2012) [enhanced version].

More important, Chief Judge Rader took the opportunity to explain how a court should apply the doctrine of equivalents. He noted that the lower court judge believed that "into engagement with" was binary in nature, that is, the walls of the deck were either in contact or they were not. The district court feared that allowing a finding of infringement when there was no contact would "vitiate," that is, give no effect to, that phrase of the patent claim.

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Robert M. Asher of Sunstein Kann Murphy & Timbers LLP specializes in patent litigation and prosecution with a particular emphasis on inter partes review, which operates at the intersection between litigation and prosecution. He is an astute and accomplished advocate for inventors and businesses affected by patents. Clients, such as ActiveVideo Networks, Superspeed Software and Silent Systems, have been richly rewarded from Bob's prosecution work on their patents. He co-chairs the firm's Patent Practice Group.