Federal Circuit Cites Limits Of Extrinsic Evidence In Prosecution Disclaimer
On April 1, 2022, the Court of Appeals for the Federal Circuit (CAFC) reversed a district court’s claim construction and corresponding summary judgement of non-infringement decisions. The lower court had improperly relied on extrinsic evidence to determine what had been disclaimed by the applicant during prosecution. Genuine Enabling Tech. v. Nintendo Co., Ltd., No. 2020-2167 (Fed. Cir. Apr. 1, 2022).
During claim construction, a patent owner may not recapture specific meanings that were disclaimed during prosecution. This is the doctrine of prosecution disclaimer. Under the doctrine, a disclaiming statement must be “so clear as to show reasonable clarity and deliberateness,” and “so unmistakable as to be unambiguous evidence of disclaimer.” Omega Eng’g, Inc, v. Raytek Corp., 334 F.3d 1314, 1325 (Fed. Cir. 2003).
This appeal comes from a dispute in the Western District of Washington between Genuine Enabling Technology, the owner of U.S. Patent No. 6,219,730 (“the ’730 Patent”), and Nintendo. The ’730 Patent describes a computer mouse that also functions as a microphone, and it claims, in relevant part, “a user input apparatus” that additionally receives “one input signal.” Genuine Enabling claimed that Nintendo’s Wii controller products infringed.
During prosecution, the ’730 Patent was rejected for obviousness in view of U.S. Patent No. 5,990,866 to Yollin (“Yollin”), which discloses a mouse with “integrated physiological response detection facilities.” Yollin provided that one example of a physiological response detection facility was an electromyograph, or EMG. In overcoming this rejection, the applicant argued that Yollin only received a “slow varying signal” and therefore does not disclose input signals that contain “audio or higher frequencies.”
Nintendo and Genuine Enabling agreed that the applicant of the ’730 Patent had disclaimed certain lower frequencies. Nintendo argued that the applicant had disclaimed frequencies below the maximum frequency of a signal generated by an EMG, identified by expert report as 500 Hz. Genuine Enabling argued that only frequencies below “audio,” or human hearing, were disclaimed. The district court agreed with Nintendo and construed “input signal” as a signal above 500 Hz.
The CAFC reversed. While expert testimony may be useful in claim construction to provide background on the technology, explain the invention, or establish that a particular term has a particular meaning in the pertinent field, it “may not be used to diverge significantly from the intrinsic record.” Because the applicant disclaimed nothing but frequencies below “audio,” the district court erred in construction that limited the patent to frequencies higher than 500Hz.