US PatentIn patent disputes involving complex technologies, especially when the disputed patent was developed in an early stage of the technical field, research papers and similar publications are oftentimes relied on to make obviousness-based invalidity challenges. It is common for such research papers to include predictions or aspirations with regards to potential future developments in the field. These aspirational statements are routinely relied upon to support motivations to combine prior art and assertions that the direction of advancement predicted by these statements renders a patent’s claimed invention obvious.

The Federal Circuit’s decision in the precedential Raytheon Technology Corporation v. General Electric Company case indicates that when relying on future-looking or “aspirational” research papers in an obviousness attack, it is important to introduce sufficient evidence to establish that the relied-upon portions of the prior art would enable a person of ordinary skill in the art (AKA the “skilled artisan”) to make and use the challenged claimed inventor or element thereof.

The Inter Partes Review

In 2018, GE filed a petition for inter parties review (IPR) of U.S. 9,695,751 (’571 Patent) assigned to Raytheon. The ’571 Patent is directed to a “geared turbofan gas turbine engine architecture” capable of a “power density range” much higher than found in the prior art. In its IPR petition, GE challenged several of the patent’s claims as being obvious in light of a single NASA Technical Memorandum from 1987 by Gerald Knip, Jr., entitled “Analysis of an Advance Technology Subsonic Turbofan Incorporating Revolution Materials” (“Knip”). Knip describes itself as a “study” into the possibility of improved engine performance and reduced weight benefits of developing turbofan engines made of entirely revolutionary composite materials developed in the future. Knip provides what the author anticipated would be “approximate cycle and configuration” parameters of such an engine and the potential fuel savings of such an engine when compared to existing jet engines in the late 1980s. Essentially, Knip is, as GE’s expert characterized, an aspirational “what if” paper into advanced engine design in the future using “revolutionary” materials that had yet to be implemented.

In its IPR petition, GE asserted that Knip disclosed performance parameters that would permit a skilled artisan to derive engine power densities that render obvious the power density range claimed in the ’571 Patent. GE further asserted, in the alternative, that because power density is a “result-effective variable,” that even if Knip did not disclose an engine that resulted in a power density within the claimed range, it would have nevertheless been obvious to a skilled artisan to modify the thrust and/or turbine volume of Knip’s thought-experiment or “imaginary” engine to optimize the power density. In support of these assertions, GE’s expert even constructed a computer engine model of the engine imagined in Knip, though at no point was an actual working, physical version of the engine ever made.

In its Patent Owner’s response to the petition, Raytheon countered GE’s assertions with what the Federal Circuit described as “extensive, unrebutted evidence of non-enablement.” This evidence included an expert declaration from a professor of materials science that detailed the unavailability of such revolutionary composite materials contemplated by Knip, as well as evidence that the exceptional temperature and pressure parameters cited in Knip had not been achieved through other means as of the ’751 Patent’s priority date.

In its Final Written Decision, the PTAB concluded that Knip was “enabling” and, therefore, rendered the challenged claims of the patent obvious to a skilled artisan. According to the Federal Circuit, the PTAB’s overall conclusion narrowly focused on whether Knip provided enough disclosure to enable a skilled artisan to calculate what would be the power density of Knip’s engine and that GE’s expert showed persuasively that a skilled artisan would have used the engine cycle and turbine volume measurement parameters expressly provided in Knip, along with certain reasonable assumptions and estimates as to missing parameters, to result in values within the claimed range, thereby rendering the challenged claimed obvious.

Appeal to the Federal Circuit

Raytheon appealed the Board’s decision, presenting a single issue: whether the Board erred in finding Knip “enabling” of the claimed invention. According to Raytheon, the PTAB applied the wrong legal standard and improperly focused only on whether Knip enables a skilled artisan to calculate the power density of Knip’s contemplated, futuristic engine, rather than considering whether Knip enables a skilled artisan to actually make the claimed invention. The Federal Circuit agreed with Raytheon’s argument and reversed the PTAB’s conclusion of obviousness.

The Federal Circuit ruled that

“[i]n the absence of [any] other supporting evidence to enable a skilled artisan to make the claimed invention, a standalone § 103 reference must enable the portions of its disclosure being relied upon.” Conversely, “if an obviousness case is based [solely] on a non-self-enabled reference, and no other prior art reference or evidence would have enabled a skilled artisan to make the claimed invention, then the invention cannot be said to have been obvious.”

In its opinion, the Federal Circuit reiterated the rule that the prior art, when taken as a whole, must enable a skilled artisan to make and use the claimed invention. There is no absolute requirement for a relied-upon reference to be self-enabling in the § 103 context, as long as the overall evidence of what was known at the time of invention establishes that a skilled artisan could have made and used the claimed invention. For example, if a reference does not provide an enabling disclosure for a particular claim limitation, it still may be relied on to furnish a motivation to combine and be combined with another reference that does enable that claim limitation.

However, in the situation encountered in this case, where obviousness is based solely on a single, standalone § 103 reference, that reference must enable the portions of its disclosure that are being relied upon for obviousness. Thus, if the prior art reference is not self-enabled, and no other prior art reference or evidence is introduced to establish that a skilled artisan would have been enabled to make the claimed invention, then the invention cannot be said to have been obvious. As the Federal Circuit, explained, “In the absence of such other supporting evidence to enable a skilled artisan to make the claimed invention, a standalone § 103 reference must enable the portions of its disclosure being relied upon.”


Validity challenges in IPRs and lawsuits oftentimes rely on technical research papers and publications. This is especially true in situations where this is not a lot of patent prior art such as in cases involving complex or early developing technologies. When relying on such research papers to support an invalidity challenge, it is incumbent upon practitioners to work with their experts to make sure that the prior art reference is self-enabling and, if not, to include additional prior art references that do provide enabling disclosures for the claim elements being challenge in the non-enabled reference. Conversely, when defending a validity challenge to a patent, if the challenge relies on aspirational or “what if” future looking statements in a reference, practitioners should determine whether the reference is adequately enabling. If not, practitioners should determine whether any supporting evidence assists in enabling the non-enabled reference and whether there is sufficient evidence to combine the teachings of the non-enabled reference with the enabling evidence being offered.