In a recent non-precedential decision, Snap-on Inc. v. Milwaukee Elec. Tool Corp., No. 2017-1305, 2018 WL 935454 (Fed. Cir. Feb. 16, 2018), the Federal Circuit affirmed the PTAB’s final written decisions in several IPRs that upheld challenged claims of Milwaukee Tool patents as nonobvious, although the court determined that the PTAB erred in construing a disputed claim term.

The IPRs addressed claim construction of a so-called “20-Amp Limitation” relating to the characteristics of lithium-ion battery cells arrayed within a battery pack used to drive cordless power tools. As summarized below, a district court previously construed this limitation, the PTAB agreed with the court’s construction, yet the Federal Circuit revised the construction on appeal:

Petitioner, Snap-On, argued on appeal that the PTAB erred by reading the phrase “over the course of delivering [the cells’] entire rated capacity” into the claim. But the Federal Circuit disagreed, determining instead (i) that the PTAB did not err in adopting the district court’s conclusion that battery capacity is “normally measured by discharging at a constant current until the battery has reached its terminal voltage,” and (ii) that the record, including the intrinsic evidence and an IEEE dictionary definition, supported the PTAB’s construction.

Snap-On also argued that the PTAB erred in reading the term “average” out of the claim. Here, the Federal Circuit agreed, and included the term “on average” in its revised construction. But the Federal Circuit held that, “although the Board erred in omitting the word ‘average’ from its construction, the Board’s fact findings regarding obviousness are still supported by substantial evidence and the Board’s legal determinations of obviousness are correct under the proper claim construction. The harmless error rule applies to appeals from the Board.” Specifically, the court cited the PTAB’s fact-findings that (i) none of the prior art combinations taught battery cells that would reach (let alone average) 20-Amp output, and (ii) a person having ordinary skill in the art would have had no motivation to combine and no reasonable expectation of success in achieving the 20-Amp limitation in view of the prior art combinations Snap-On advanced.

This case illustrates the challenge in overturning a PTAB decision on appeal—even identifying an error in claim construction may not be sufficient to avoid affirmance of the PTAB’s decision.