IPR is widely used to challenge patents. Post-grant review (PGR) was intended to work in conjunction with IPR, providing a fuller set of challenges, but only in the first nine months following a patent’s issuance. In fact, a patent cannot be challenged via IPR while it is still eligible for PGR. But, to date, PGR has been little used, in part because it is only available for patents with an effective filing date after March 15, 2013. With over half of all patents issuing now eligible for PGR, is its usage set to climb? Should petitioners jump on the more robust challenges in PGR, or wait nine months and proceed with an IPR? A review of early data on PGR petitions reveals some interesting insights.

Though PGR allows for a broader array of challenges, including challenges under §§ 112 and 101, most petitioners are using PGR for challenges under §§ 102 and 103, which are the same type of attacks they can make in an IPR proceeding. As of July 26, 2017, petitioners have challenged patents on prior art grounds in 77% of PGR petitions for which an institution decision was made (or 37 of 48), whereas other grounds unique to PGRs have only been asserted in 65% of cases. Notably, 89% of those petitions containing prior art challenges relied solely on prior art patents and printed publications, with only four petitions involving other types of prior art not available in an IPR proceeding.

Further, the institution rate of PGR is lower on prior art grounds than the institution rate in IPRs. Of the 37 petitions challenging patents on prior art grounds, 20 were instituted for at least one claim. This gives an institution rate of 54% for PGR petitions raising prior art challenges, lower than the 60% institution rate for IPRs.

This result might be explained by the heightened requirement to show invalidity for a PGR to be instituted. But that begs the question: why would a petitioner challenging a patent under 102 or 103 opt for filing a PGR over an IPR given the lower chance of institution?

That question may be even more salient when the impact of a loss in a post-grant trial is considered. Estoppel–barring further challenges to a patent–might be greater in PGR. As we recently discussed, district courts have divergent views of IPR estoppel, ranging from a limited view in which there is no estoppel for non-instituted grounds to a broad view in which all grounds the petitioner raised or could have raised are estopped, excepting only those not instituted for procedural reasons. If courts endorse a limited view of estoppel for IPRs and PGRs, the estoppel effect of the two proceedings would be similar if raising the same grounds. However, if courts follow the broader view of estoppel, a petitioner winning institution of a PGR may be at a significant disadvantage with respect to estoppel if that PGR does not result in all claims being invalidated.

One possibility is that the petitioner sees significant value in filing immediately rather than waiting to challenge the patent via an IPR. For a petition for PGR to be filed within nine months of issuance, it is likely that the petitioner was concerned enough about the patent to be tracking it prior to issuance, either because that patent was identified as a threat to the petitioner or because the parties were already in litigation over related patents such that the petitioner could not afford to wait for IPR. It may also be that many PGR petitioners are making challenges under 101 or 112, which they could not do if they waited for IPR.

However, an important lesson from these early statistics is that even though PGR may be available, it may not be the best option. It is important to consider the pros and cons of filing for PGR rather than waiting for IPR. Petitioners should weigh the legal considerations, such as the available grounds, the institution rate of those grounds, and the estoppel effect of the decision, against their ultimate business and commercial goals. As always, it is best to consult a practitioner fully versed in all the options.