One of the many criticisms of the post-grant review proceedings instituted by the Leahy-Smith America Invents Act, both post-grant review (PGR) available within 9 months of patent grant based on all provisions of the Patent Act and inter partes review (IPR) throughout the entire term of the patent but limited to prior art-based rejections under Section 102 and 103), is that patentees can be harassed by multiple challenges by multiple parties on the same patent and similar prior art (including both serial and parallel varieties of such challenges).  The U.S. Patent and Trademark Office, being sensitive to these criticisms has provided statistical analyses of PGR and IPR challenges and the most recent was posted today on the PTO website (see Patent Trial and Appeal Board
Multiple Petitions Study).

The Report begins with serial IPR petitions, defined as "one petition or a group of two or more petitions filed more than 90 days after the first petition by the same petitioner challenging same patent, with one count per group per fiscal year.  The statistics, accumulated from FY15 to FY22, illustrate the effect of two PTAB decisions:  NVIDIA Corp. v. Samsung Elecs. Co., Case IPR2016-00134, Paper 9 (PTAB May 4, 2016), and General Plastic Industrial Co., Ltd. v. Canon Kabushiki Kaisha, Case IPR2016-01357 et al., Paper 19 (PTAB Sept. 6, 2017) (precedential).  As explained by the Office, the General Plastic decision provided non-exclusive factors for the Board to consider when exercising its discretion to institute an IPR and directed to "follow-on" petitions for PGR, IPR, and the now sunsetted Covered Business Methods proceedings.  These statistics are set forth in graphs of attempts at PGR/IPR institution:

and instituted PGRs/IPRs:

showing a gradual and the accelerating decline in serial petitions after the precedential General Plastics decision was handed down.  The PTO explains that serial petitions were instituted for a number of reasons, including patent owner acquiescence, the patent owner asserting new claims in district court litigation, there being a large number of claims at issue, and in one case, Apple Inc. v. Fintiv, Inc., IPR2020-00019, Paper 11 (PTAB Mar. 20, 2020) (precedential), the petitioner dismissing an ITC proceeding which had provided the basis for institution denial of the original petition.  The PTO assessment of the collated data show that 74 out of 4,233 challenges (~1.75%) involved serial petitions, with only 25 or ~0.6% resulting in institution.

Similar statistical assessments were presented to "parallel institutions," i.e., where a group of petitions are filed 90 days or less apart by the same petitioner against the same patent.  These statistics are set forth in graphs of attempts at parallel PGR/IPR institution:

and instituted parallel PGRs/IPRs:

For parallel petitions, the PTO identified Comcast Cable Commc'ns, LLC v. RoviGuides, Inc., IPR2019-00224, Paper 10 (PTAB Apr. 3, 2019), and an update to the Trial Practice Guide as relevant events during a single fiscal year that were responsible for the decline in granted parallel PGRs and IPRs.  The PTO identified instances where a petitioner prevailed on institution of parallel petitions over patent owner objection as cases where there were a large number of claims, priority date issues prior art eligibility, or different claims contested.  The Office notes that in FY21 70% of those instituted parallel PGRs/IPRs were instance where the patent owner did not contest institution, whereas those statistics dropped to 54% in FY22.

The Office presented an assessment of these statistics showing that the majority of petitions in FY15 and FY22 were single petitions, but that the instances of multiple petitions had a steady trend downward during that time:

While these statistics are certainly useful at a low level of granularity to show that multiple serial and parallel petitions are declining over the period the statistics were studied, it is unlikely that the picture they present will be considered sufficiently rosy to rebut or even stem the Findings and proposed amendments to the statute being considered by Congress (see "Senator Coons And Co-Sponsors Introduce the PREVAIL Act").

For those interested in further statistics, these are provided in an Appendix and the Office has also provided an Executive Summary of the study.