Non-Prior Art Evidence of the Prior Art? The Federal Circuit Says It May be Okay

Section 311(b) of the American Invents Act (“AIA”) provides that a petitioner may request cancellation of one or more claims of a patent “only on a ground that could be raised under section 102 and 103 and only on the basis of prior art consisting of patents or printed publications.” In light of this clear restriction on the evidence that can lead to the cancellation of a claim, one might reasonably assume that all of the petitioner’s evidence during that trial must be prior art. A recent decision from the Federal Circuit, however, shows that this assumption is not entirely correct. Rather, in some situations, the cancellation of a claim may turn on evidence that is not even prior art to the claim.

In Yeda Research & Development v. Mylan, the petitioner relied on prior art that disclosed all limitations of the challenged patent’s medical treatment method except for a limitation regarding the frequency that the patient had to receive injections. The challenged patent called for six injections in two weeks, but the prior art disclosed seven injections in two weeks.

The patent owner argued that there was no motivation to modify the prior art method to reduce the number of injections. In response, the petitioner cited a reference that published just three weeks after the threshold date that would have made it prior art, but that described research from years earlier about ways to reduce the number of injections. The petitioner argued that this non-prior art evidence demonstrated that ordinary artisans at the time of the invention were motivated to reduce the number of injections. In the IPR, the PTAB agreed with the petitioner and relied in part on the non-prior art.

On appeal, the patent owner argued that the PTAB’s reliance on the non-prior art reference was inappropriate under section 311(b). The Federal Circuit disagreed and explained non-prior art might be evidence of how one with ordinary skill in the art would have understood the prior art. Section 311(b) merely defines what type of prior art may form the basis of a ground for canceling a patent claim (i.e., “patents or printed publications”), the Court explained, but does not prevent the PTAB from considering other relevant evidence.


This decision is not a license to use non-prior art in any context. The non-prior art reference here spoke to whether researchers working at a time before the challenged patents would have had a motivation to modify the prior art method. Other uses of non-prior art may not be permitted.

Indeed, the Court’s decision conspicuously avoided endorsing the PTAB’s reliance on non-prior art to address the separate question of whether one would have expected the modification to the prior art to be successful. The Court’s differing approaches to these questions (i.e., whether a motivation to modify the prior art existed, versus whether one would have expected success when doing so) highlight this as an issue to watch further.