In an opinion addressing claim construction and priority dates, the US Court of Appeals for the Federal Circuit explained that preamble language is not limiting when it merely recites an intended use, and that diligence need only be reasonably continuous when reducing an invention to practice. Arctic Cat Inc. v. GEP Power Prods., Inc., Case Nos. 18-1520, 1521 (Fed. Cir. Mar. 26, 2019) (Taranto, J).

GEP filed petitions for inter partes review of two Arctic Cat patents directed to power distribution modules, challenging all claims of each patent as unpatentable for anticipation and obviousness over several prior art patents. Both reviews were instituted, and the Patent Trial and Appeal Board (PTAB) issued final written decisions finding all claims of both patents unpatentable. The PTAB rejected Arctic Cat’s argument that certain language in the preambles of several claims was limiting, finding that the preambles recited only an intended use for an otherwise complete claimed apparatus. The PTAB further rejected Arctic Cat’s argument that the patents were entitled to a priority date predating one of the prior art patents, because the PTAB found that the inventor had failed to diligently reduce the invention to practice. Arctic Cat appealed.

The Federal Circuit affirmed the PTAB’s finding that the preamble was not limiting, explaining that a preamble is only limiting if it recites essential structure or steps, or if it is necessary to give life, meaning and vitality to the claim. A preamble is not limiting where the claim recites a structurally complete invention and the preamble only states a purpose or intended use for the recited structures. In the case at hand, the claims at issue contained preambles referring to a “personal recreation vehicle” as an intended use for the claimed invention. The Court noted the lack of reference to the “personal recreation vehicle” in the body of the claims, and that Arctic Cat did not rely on the preamble to distinguish prior art during prosecution. Moreover, the specification failed to disclose any aspect of the “personal recreation vehicle” that is asserted to be an improvement, other than the claimed power distribution module. Finally, Arctic Cat chose not to use the well-established Jepson transitional language, which is a powerful reason to deny the preamble the limiting effect it would have had.

Regarding the appropriate priority date for the applications for the Arctic Cat patents, the Federal Circuit reversed the PTAB. It was undisputed that Arctic Cat’s conception date predated the priority date of the asserted prior art, and the only issue was whether the inventor was diligent in reducing the invention to practice from conception until the date of the filing of the application (constructive reduction to practice). In reversing the PTAB, the Court explained that diligence need only be reasonably continuous; the point of the analysis is not to scour the patent owner’s corroborating evidence in search of intervals that must be explained. The pertinent question is whether, in light of the evidence as a whole, the invention was abandoned or unreasonably delayed. Here, the Court explained that the PTAB’s analysis rested on too rigid a standard. The PTAB faulted the inventor for two gaps in the record. However, evidence showed that the invention was undergoing testing, an activity that does not give rise to an inference of abandonment or unreasonable delay.