When to Consider Expert Testimony for Special Purpose Computer-Implemented Means-Plus-Function Claims

In Sisvel International S.A. v. Sierra Wireless, Inc., Nos. 2022-1493, 2022-1547 (Fed. Cir. Oct. 6, 2023), the Federal Circuit affirmed-in-part, vacated-in-part, and remanded to the Patent Trial and Appeal Board (“Board”).

Cross-Appellants filed a petition for an IPR of claims 1-10 of U.S. Patent No. 6,529,561 (“the ’561 patent”). The ’561 patent relates to methods of channel coding when transmitting data in radio systems. After instituting the IPR, the Board found claims 1-3 and 9 unpatentable for obviousness and claims 4-8 and 10 not unpatentable. The claims were examined under pre-AIA law.

The Federal Circuit held that the Board erred in analyzing the “means for detection” limitation of claims 5 and 10. The Court noted that its precedents recognize two distinct groups for special purpose computer-implemented means-plus-functions claims: (1) where a defining structure is totally absent from the specification and expert testimony cannot be considered; or (2) where a defining structure is “arguably” adequately disclosed in the specification and expert testimony may be considered. While the Board determined that the “means for detection” limitation fell into the first group and did not consider expert testimony, the Federal Circuit disagreed because the specification identified the name of relevant software protocols. Thus, the limitation properly fell into the second group even though the steps corresponding to the protocols were not expressly described in the specification. The Federal Circuit thus remanded for the Board to consider expert testimony and address whether the protocols identified disclosed a sufficient structure to satisfy 35 U.S.C. § 112.