The Federal Circuit Giveth, And The Federal Circuit Taketh Away

That is the gist of a recent decision by the court, which permitted an IPR Petitioner to use “general knowledge” to fill in missing claim limitations in certain circumstances, but also constrained the PTAB as to what grounds may serve as the basis for instituting trial.

Petitioners seeking IPR of a patent must make their case for unpatentability based on two types of prior art – patents and printed publications. However, in Koninklijke Philips N.V. v. Google LLC (No. 2019-1177), the Federal Circuit held that those references can be used as evidence of the general knowledge, and need not be made part of a specific combination. Specifically, the court found that the Petitioner had properly alleged that although the primary reference relied upon did not disclose each and every element of the claimed invention, the differences between the claimed invention and that reference would have been obvious to a skilled person based on their general knowledge.

However, the opinion indicates that not all such attempts will be successful, such as where a party attempting to use “common sense” to supply a missing claim limitation bases their argument only on conclusory statements and unspecified expert testimony. In this case, an important factor weighing in the Petitioner’s favor was the PTAB’s reliance on an expert declaration and evidence of the skilled artisan’s general knowledge in the form of a piece of prior art  that was in the record, even though that secondary reference was not part of the asserted obviousness combination.

Importantly, use of “general knowledge” seems to have provided flexibility to Petitioner and the PTAB in this case. In particular, the Patent Owner argued that the secondary reference could not be combined with the primary reference, as the specific type of technology it disclosed was “incompatible” with that provided by the primary reference. But the Federal Circuit held that this argument was inapposite, as the relevant inquiry was whether the skilled person would have been motivated to make the combination with their general knowledge of the technology (rather than the specific technology disclosed in the secondary reference).

While the Federal Circuit endorsed this use of “general knowledge,” the decision was not all good news for petitioners. The Court also made clear that only grounds that are actually advanced by Petitioner in a Petition can be instituted, rejecting the PTAB’s institution of a ground based on the primary reference and the secondary reference that was not actually advanced in combination in the Petition.


  • When considering secondary references to fill in missing claim limitations, IPR Petitioners should consider relying on general knowledge where appropriate, as this can provide flexibility and avoid potentially limiting disclosure of one or more secondary references that might otherwise fill the gap. However, any allegation of general knowledge should be amply supported by expert testimony and citation to relevant prior art.
  • Petitioners should also carefully consider whether “general knowledge” grounds can stand on their own, or should be combined with back-up positions based on prior art. Presenting too many grounds risks diluting the overall strength of the Petition and could result in non-institution.
  • Patent Owners should be diligent in critiquing grounds that rely on general knowledge to supply missing claim limitations, including attacking any supporting expert testimony and prior art citations.