In Follow-On IPR Petitions, Different Prior Art May Not Be Considered Substantially Different

An IPR follow-on petitioner may find it particularly challenging to select the best prior art references and arguments to submit to the PTAB. To make matters worse, the PTAB may decide to invoke its discretionary denial under 35 U.S.C. § 325(d) if it considers the prior art and/or arguments submitted in the follow-on petition to be the same or substantially the same as those considered during prosecution, in parallel proceedings, or in an earlier-filed IPR petition, even if the follow-on petition is filed by a different entity.

It can be difficult to gauge when the PTAB will view prior art references as the same or substantially the same as those previously considered. The recent decision in Neptune Generics, LLC v. Aventis Pharma SA (IPR2019-00136) may shed some light on this.

Prior to Neptune’s petition, the Board denied a first IPR petition filed by Mylan against the same patent. The Neptune petition challenged the same claims with a set of prior art references partially different from the Mylan petition. In the follow-on petition, Neptune argued that it was using a different combination of prior art and attempted to draw a distinction between its arguments and the Mylan petition.

The patent owner countered that the difference between the Mylan petition and the Neptune petition was “superficial”, for two reasons: (i) the two petitioners cited to the overlapping reference for the same reason; and (ii) Neptune used the different prior art reference in support of the same argument Mylan had made. Further, all of the prior art references submitted by Neptune had been considered in a district court litigation where the claims were upheld.

The Board sided with the patent owner and stated that Neptune’s different prior art “elides the substantial similarities between the art and arguments presented in both this petition and the Mylan petition.” Interestingly, the Board noted that there was one ground in the Neptune petition that was different from the Mylan petition. However, Neptune failed to elaborate and support this ground with any evidence or thorough analysis. As a result, the Board exercised its discretion to deny the institution of IPR.


This decision suggests that submitting a different set of references and seemingly different arguments may not be enough to convince the Board to institute an IPR. It serves as a reminder to petitioners challenging a patent that the selection of prior art references, along with the arguments built around them, can make or break an IPR. A follow-on petitioner should take care to rely on new prior art references and arguments in its petition and to highlight the differences between its petition and any earlier petitions.