The popularity of post-grant review (“PGR”) proceedings at the U.S. Patent Office is expected to surge as the number of eligible patents rapidly grows and patent challengers recognize the power of the additional tools available in PGRs as compared to inter partes review (“IPR”). Moreover, those additional tools may lead to an even higher invalidation rate for PGRs than the current rate seen with IPRs. This article outlines those additional tools and highlights the major differences among PGR, IPR and Europe’s closest relative to these domestic proceedings, the European Patent Office’s Opposition proceedings.

Eligibility, Timing & Early Statistics

Unlike IPRs, which can be filed for any U.S. patent subject to certain timing restrictions described below, PGR is only available for patents subject to the first-to-file provisions of the America Invents Act (“AIA”) (i.e., patents having an effective filing date on or after March 16, 2013).1 Given the limited number of first-to-file patents issued, only ten PGR petitions have been filed as of this writing.2 However, a trend of increased filings already appears to be emerging, with no petitions filed in 2013, only two petitions filed in 2014, and a current total of eight petitions filed in 2015 (with five filed in the third quarter).3 While these numbers may appear small, only about 15% of patents issuing today even qualify for PGR4 and that number diminishes to about 1% for patents that issued a year ago.5

Similar to European Opposition practice, PGR petitions may only be filed during a limited window immediately after grant of the patent to be challenged, i.e., PGRs can only be filed within nine months after patent grant.6 Indeed, this is not a lot of time when considering how long it can take a patent challenger to identify the issuance of the patent and prepare the PGR petition (including performing prior art searches and identifying and working with an expert on a declaration to support the petition). Thus, it is unlikely the number of PGRs filed will reach the level of IPR filings, which can be filed at any time for first-to-invent patents and any time after the PGR period for first-to-file patents.7

Grounds - An Expanded Tool Box

While IPR petitioners are limited to asserting challenges based on anticipation and/or obviousness over patents or other printed publications,8 PGR petitioners are authorized to assert a variety of other challenges.9 First, challenges based on anticipation and/or obviousness are not limited to any particular type of prior art, and can include, for example, a prior public use or sale.10 Further, PGR petitioners can challenge subject matter eligibility under 35 U.S.C. § 101. These challenges can be particularly powerful given the Supreme Court decision in Alice11 and the July 2015 Update12 to the U.S. Patent and Trademark Office’s (“PTO”) interim guidance on the subject. Indeed, anecdotal evidence of the power of subject matter eligibility challenges at the PTAB can be seen by comparing the statistics of Computer Business Method (“CBM”) petitions (which allow subject matter eligibility challenges) with IPRs—96% of final decisions in CBMs found at least some challenged claims unpatentable vs. 84% in IPRs.13 Finally, PGR filers can challenge the patent on 35 U.S.C. § 112 grounds, including indefiniteness and failing to meet the written description and/or enablement requirements (but excluding best mode), none of which are available in IPR.14


Anyone considering challenging a patent via PGR should be aware, however, of the enhanced estoppel as compared to IPR. A filer of an IPR that results in a final written decision is estopped from challenging the patent at the PTO and in an International Trade Commission (ITC) or civil action based any ground raised or that reasonably could have raised15 (which for IPR is limited to anticipation and obviousness based upon patents or printed publications). Although the estoppel provision is the same for PGR,16 due to the availability of additional grounds for challenging a patent in PGR, the range of estoppel is wider and includes any anticipation and obviousness challenges, subject matter eligibility challenges and 35 U.S.C. § 112 challenges. Indeed, it is quite possible that an unsuccessful PGR petitioner will be left with no invalidity challenges available in a subsequent civil or ITC litigation. At first blush this may seem like an unacceptable risk to take, but a patent challenger’s chance of success may be significantly higher at the PTAB than it is with a jury or in any other forum due to the relaxed standard of proof and broader claim interpretations employed at the PTAB. Further, the current favorable landscape for subject matter eligibility challenges under 35 U.S.C. § 101 can weigh in favor of filing a PGR now as opposed to saving that challenge for a litigation that may not commence until the pendulum has an opportunity to swing the other direction with respect to § 101 challenges.

Conclusion and Practice Notes

As described above and supplemented by the chart provided below, PGR, IPR, and European Opposition practice include a number of similarities, but also many important differences. First, and as noted above, the number of PGR petitions is expected to grow quickly over the coming years given the rapid rise in the percent of patents issuing that are eligible for PGR. Additionally, given the additional and alternative grounds of invalidation available, including subject matter eligibility challenges, PGRs may even be more successful for challenging patent claims than IPRs.

Moreover, companies in fields susceptible to subject matter eligibility challenges such as e-commerce, computers, software, business processing and modeling, financials, and banking may want to consider actively monitoring competitor (and/or related technology) patents issuing so that PGR challenges can be considered. Without such programs, by the time a potentially problematic patent is identified, it may be too late to effectively prepare and file a PGR.

Because of the low cost, reduced resources (e.g., no expert witnesses) and lack of estoppel in European Opposition practice, Oppositions may be useful as a test ground for prior art and invalidity arguments that could be later brought in a PGR or IPR. While there may be limited circumstance where this option is available (e.g., having an issued European patent that has substantially the same claims as a U.S. application or patent), European Oppositions could be treated as a “mock PTAB trial,” which can even be done anonymously. Likewise, if a patent owner is involved in a European opposition, it can be used to test various claim amendments by filing alternative auxiliary claim requests, given the limited ability and difficulty in amending the claims during PGR and IPR.

In conclusion, patent challengers may want to consider the power of the additional tools available in PGRs, when deciding among filing a PGR or IPR or challenging the patent in civil litigation. Despite the risk of enhanced estoppel, a PGR may be the patent challenger’s best chance to invalidate the patent given the additional grounds of invalidation available as compared to IPR and the lower burden of proof and reduced resources required as compared to civil litigation. 

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