In Raytheon Technologies v. General Electric Corp., Appeal 2020-1755, (Fed. Cir. April 16, 2021), the Federal Circuit reversed a PTAB inter partes review decision that determined Raytheon’s claims, directed to gas turbine engines, are unpatentable as obviousness over “Knip,” a 1987 NASA technical memo.  In particular, the court determined that Knip did not enable a skilled artisan to make the claimed invention.

The Raytheon patent generally claims a gas turbine engine having, among other things, “a power density at Sea Level Takeoff greater than or equal to 1.5 lbf/in3 and less than or equal to 5.5 lbf/in3.”  The key distinguishing feature of Raytheon’s claims, according to the PTAB, was that power density range, which “the patent describe[d] as being ‘much higher than in the prior art.’”  Id. at 4 (citing the Raytheon patent).

GE argued to the PTAB that Knip, describing an “advanced engine,” rendered Raytheon’s claims obvious.  GE also argued that a skilled artisan would derive Raytheon’s claimed power density from Knip’s engine.  Id. at 6-7.  However, Knip’s engine was undisputedly impossible to build at the time Knip was published because it required use of “revolutionary” composite materials to achieve performance parameters, including pressure ratios and turbine temperatures, and these revolutionary composite materials did not exist.  Id. at 6.

On appeal, the court explained that “[t]o render a claim obvious, the prior art, taken as a whole, must enable a skilled artisan to make and use the claimed invention.”  Id. at 10 (citing In re Kumar, 418 F.3d 1361, 1368 (Fed. Cir. 2005)).  Yet, a prior art reference does not have to enable its own disclosure to sustain an obviousness challenge.  Id. (citing Symbol Techs., Inc. v. Opticon, Inc., 935 F.2d 1569, 1578 (Fed. Cir. 1991), and Beckman Instruments Inc. v. LKB Produkter AB, 892 F.2d 1547, 1551 (Fed. Cir. 1989)).

Based on these precedents, the court stated that the PTAB erred in its enablement analysis.  Specifically, the court stated that the PTAB “focused only on ‘whether [a skilled artisan] is provided with sufficient parameters in Knip to determine, without undue experimentation, a power density.’”  Id. at 12 (quoting Gen. Elec., 2020 WL 859443, at *7).  The court further stated that the PTAB did not address whether Knip enabled the claimed invention.  Id.

To support its position of non-enablement, Raytheon presented a declaration from a professor of materials science demonstrating the unavailability of the revolutionary composite material required by Knip.  In addition, Raytheon submitted evidence that Knip’s temperature and pressure parameters had not been achieved any other way as of the priority date.  Id. at 13.

This evidence essentially went unrebutted by GE.  GE did “construct” a computer model of Knip’s imagined engine.  Yet, GE’s expert did not contend that it could physically be built.  Thus, the court found “that GE failed to provide an evidence-based case for how the turbofan engine claimed in the ’751 patent having a particular power density is enabled by Knip’s disclosure.”  Id.

GE further argued that the power density was simply a result-effective variable that could be optimized by a skilled artisan.  However, the court rejected this argument also on non-enablement grounds, stating, “[i]f a skilled artisan cannot make Knip’s engine, a skilled artisan necessarily cannot optimize its power density.”  Id. at 14.

Even though prior art references are often enabling for what they disclose, this decision may present a tool for patentees to argue for the patentability of their claims where a given prior art reference lacks enablement.  For example, if a particular component in a prior art reference could only have been imagined (and not physically constructed), and there was no other teaching (e.g., in the general state of the art) on how to construct the component, this component would not be enabled; and thus, a claim containing this component would survive a prior art challenge based on the reference.