The America Invents Act established post-grant review (PGR) as a new tool for challenging the validity of granted patents. A PGR petition can be filed up to nine months after issuance of a PGR-eligible patent. During that nine-month period, PGR is the only adversarial proceeding available to challenge validity within the USPTO, as Covered Business Method (CBM) and inter partes review (IPR) petitions cannot be filed until nine months after issuance. Much like CBM reviews, petitioners can challenge the validity of the patent on the basis of §§ 101, 102, 103, and 112 in a PGR review.1  In contrast, PGR proceedings provide more statutory grounds for challenging patents than the popular IPR process. However, unlike CBMs and IPRs, PGRs are only available for first-inventor-to file patents (i.e. patents with an effective filing date on or after March 16, 2013).2  For this reason and others, PGRs have not seen wide use. As of November 17, 2016, only 41 PGR petitions have been filed. Of those, the Patent Trial and Appeal Board (PTAB) has granted institution for 15 petitions, denied institution for seven petitions, and issued four Final Written Decisions.3

While Congress intended the PGR process to be similar to European opposition proceedings,4 to date, PGR has not been nearly as popular. In contrast to the small number of PGR filings, the European Patent Offce (EPO) reports that the opposition rate in 2015 for granted European patents was 4.4 percent, and in that same year, the EPO issued 3,713 opposition decisions.5 Given the paucity of PGR petitions filed to date, Congress obviously miscalculated, at least in the near term. Time will tell if the number of PGR petitions catch up to their European counterparts. Some practitioners predict PGR reviews will increase in popularity as more patents issue that are PGR-eligible. As shown in Figure 1, this prediction seems to have at least some merit, since the number of PGR petitions filed has edged up ever so slightly. This article provides an overview of PGR proceedings and highlights important practice tips drawn from the recent Final Written Decisions. The article also discusses the risk of estoppel, an extremely important issue with PGR proceedings, one which may explain PGR’s lack of popularity. 

Figure 1: Number of PGR Petitions Filed by Month

Figure 1: Number of PGR Petitions Filed by Month 6

More Grounds Are Available for Challenging a Patent’s Validity

One of the main advantages of PGR over IPR is the availability of a broader range of grounds for challenging a patent’s validity. As discussed, PGR petitions can challenge the validity of patent claims on the basis of subject matter ineligibility (35 U.S.C. § 101), anticipation (35 U.S.C. § 102) and obviousness (35 U.S.C. § 103), as well as indefiniteness, lack of enablement, or failure to meet the written description requirement (35 U.S.C. § 112). IPR petitions are limited to anticipation or obviousness challenges under Sections 102 and 103. Moreover, such challenges in an IPR can only be based on prior art patents and printed publications.7 PGR petitions can rely on an expanded universe of prior art, since they can also challenge claims as being anticipated and rendered obvious based on prior art public uses, on-sale activities, and other public disclosures in addition to patents and printed publications.

Many of the PGR petitions filed thus far are still pending before the Board. However, a review of the institution decisions issued to date reveals that challenges based on obviousness have been the most common and also the most likely to lead to trial institution. As of November 17, 2016, the Board granted institution in 60 percent of the cases where the petitioner challenged a claim as being obvious. The least successful challenges have been those based on anticipation and indefiniteness, where the Board has only granted institution in one-third of cases.8  Complete data is shown below in Figure 2. The number and types of challenges are illustrated in Figure 3. 

Figure 2: Grounds for Instituting Review

Figure 2: Grounds for Instituting Review9

Figure 3: Multiple Grounds for Unpatentability Asserted in Petitions

Figure 3: Multiple Grounds for Unpatentability Asserted in Petitions10

Practice Tips Learned From the First Final Written Decisions

PGR Proceedings Provide a Favorable Forum for § 101 Challenges

The first three PGR Final Written Decisions invalidated the challenged claims under 35 U.S.C. § 101, illustrating the continuing power of Alice. Applying the twostep framework described in Alice, the Board “first determine[d] whether the claim is ‘directed to’ a patent in eligible abstract idea.”[[N:Am. Simmental Ass’n v. Leachman Cattle of Colo., LLC, PGR2015-00003 at 24 (PTAB June 13, 2016) (Paper No. 56) [hereinafter Am. Simmental I].]] Second, the Board searched for “an ‘inventive concept’—an element or combination of elements sufficient to ensure that the claim amounts to ‘significantly more’ than the abstract idea itself.”11
The first two PGR Final Written Decisions, the American Simmental Association v. Leachman Cattle of Colorado, LLC cases, involved patents related to determining the relative market value of livestock based on genetic quality.[[N:Am. Simmental Ass’n v. Leachman Cattle of Colo., LLC, PGR2015-00005 at 2 (PTAB June 13, 2016) (Paper No. 52) [hereinafter Am. Simmental II].]]  The Board determined that the patents were directed to the fundamental concept of “determining an animal’s relative economic value based on its genetic and physical traits,”12  and agreed with the petitioner’s argument that the claims were “directed largely to applications of mathematical formulas and algorithms in the field of animal valuation.”13  The Board stated that this fundamental concept was “long prevalent in our system of commerce,” as shown by the numerous examples in the “Description of Related Art.”14  The Board also found that “all computer recitations in the challenged claims are recitations to generic computer hardware used in a conventional manner, which are insufficient to impart patentability under Alice.”15

In its third PGR Final Written Decision, the Board conducted a similar analysis. In Netsirv v. Boxbee, Inc., the challenged patent related to storage container tracking and delivery in the physical storage field,16  which the Board characterized as relating to a “bailment scheme,” which the Board found was “a long-prevalent economic practice, and constitute[s] an abstract idea.”17 After reviewing the three concepts that the patent owner argued rendered the claims significantly more than the abstract idea, the Board concluded that the claims recited “no more than the steps required to perform the abstract idea using boxes, in conjunction with routine computer application and the associated data.”18

Petitions Must Contain All Evidence Needed To Prevail and Must Advance Fully Developed Arguments

While the Board’s decisions in the American Simmental cases invalidated all of the challenged claims under § 101, the decisions also demonstrate the importance of providing sufficient corroboration that the prior art relied upon actually qualify as prior art for challenges based on § 103.19 In the American Simmental cases, the petitioner’s obviousness argument relied on a purportedly prior art system referred to as “the Angus system.” To corroborate the prior art status of the Angus system, the petitioner submitted declarations from witnesses purported to have relevant knowledge of the system as well as two website printouts allegedly showing the Angus system. The Board did not find this evidence sufficient, holding that it was weak corroborative evidence for a number of reasons. For example, one of the website printouts was generated and thus dated after the priority date, which the Board held corroborated nothing. In contrast, the Board found that the second website printout included a revision date that was before the priority date and thus offered some corroborative evidence. However, to explain the discrepancy in dates, one of the declarants had to consult with a corporate information systems department, which the Board held contradicted the declarant’s testimony that she was personally aware that the Angus system was publicly available before the priority date. Furthermore, the Board noted that the website underwent changes at various times, and there was no definitive evidence showing the nature and timing of such changes. As a result, the Board found that the petitioner didn’t meet its burden to show that the Angus system was prior art.20

The Board’s determination that the petitioner did not meet its burden to corroborate its purported prior art was not fatal to the petitioner in American Simmental II since the petitioner’s § 103 arguments did not rely exclusively on the Angus system.21  Instead, the Board performed an obviousness analysis for the claims where the petitioner provided an alternative reference, and ultimately concluded that some of the claims were obvious in view of the alternative reference. The same was not true, however, in American Simmental I, where the Board held that the petitioner did not sufficiently explain how its alternative reference met each limitation of the challenged claim. Consequently, the Board rejected the petitioner’s obviousness challenge in American Simmental I. We stress that the Board was aware that the alternative reference could have rendered the claim obvious, but that regardless, the Board emphasized that the burden was on the petitioner to prove unpatentability.22 In other words, the Board refused to do the petitioner’s job.

The Board’s fourth PGR Final Written Decision provides yet another example demonstrating the importance of providing all the evidence necessary to win at trial in the originally-filed petition. In Altaire Pharmaceuticals, Inc. v. Paragon Bioteck, Inc., the Board found the petitioner’s evidence filed with its petition lacking in several respects. First, the Board held that the petitioner failed to provide sufficient foundation to establish that its declarant qualified as an expert. Moreover, the Board held that the petitioner’s attempt to cure this defect after it was raised in the patent owner’s response was improper. In Altaire, the petitioner’s reply to the patent owner’s response included another declaration from the petitioner’s declarant describing the declarant’s experience in the industry and including the declarant’s curriculum vitae. The Board rejected the petitioner’s attempt to cure the defects of the original declaration, holding that proper reply evidence is limited to positions asserted in the originally-filed petition.23

In addition, the Board found the petition contained insufficient support for data that petitioner relied upon to show that the prior art met certain limitations of the challenged claims. The Board held that the petitioner failed to explain both how the test that generated the data was performed as well as how the data was generated. The Board also held that the petitioner’s attempt to cure these deficiencies in its reply was improper. The Board refused to consider this late-filed evidence and ultimately gave no weight to the data petitioner submitted due to the lack of credible evidence.24 Consequently, the Board concluded that the petitioner failed to show that the challenged claims were obvious over the prior art, marking the first time the Board has upheld a patent in a PGR Final Written Decision.25

The lessons in both the American Simmental cases and Altaire are applicable to all post-grant proceedings before the PTAB. First, petitioners must include all necessary evidence and provide thorough arguments showing that the challenged claims are invalid. Second, petitioners should not expect to be able to overcome any deficiencies in their originally-filed petition with their reply brief. And third, petitioners who offer multiple grounds of invalidity based on alternative references should prioritize the quality over the quantity of references and ensure that each reference is thoroughly analyzed.

Motions to Amend Are Available, But Success Will Be a Challenge

Just as in CBM and IPR proceedings, patent owners may file a motion to amend the challenged claims during a PGR review.26 The procedure for attempting to amend claims during a PGR is the same as during CBM and IPR reviews. To prevail on a motion to amend, the patent owner bears the burden to show that “(1) the substitute claims overcome all the grounds under which [the challenged claims] were determined to be unpatentable” and “(2) its request meets all the procedural requirements concerning motions to amend set forth in our rules.”27

The recent PGR Final Written Decisions suggest that patent owners will find it difficult to amend their claims during a PGR review, just as they have during CBM and IPR reviews.28 The American Simmental cases are a good illustration of the difficulty patent owners can expect. In these cases, the Board rejected the patent owner’s argument that the proposed substitute claims overcame subject matter challenges under 35 U.S.C. § 101. According to the Board, the patent owner attempted to alter the fundamental concept underlying the original claims and that regardless, the proposed claims still covered a patent-ineligible abstract idea.29 In addition, the Board found that the patent owner violated several procedural requirements for a motion to amend.30 Thus, the American Simmental cases demonstrate that overcoming subject matter eligibility challenges via claim amendments will be just as challenging in a PGR as they have been in CBM and IPR reviews. Moreover, the American Simmental cases serve as a valuable reminder to patent owners that they must strictly comply with the procedural requirements for motions to amend, as set forth in Idle Free Systems, Inc. v. Bergstrom, Inc., Case IPR2012-00027 (PTAB June 11, 2013) (Paper 26) (informative) and MasterImage 3D, Inc. v. RealD Inc., Case IPR2015-00040 (PTAB July 15, 2015) (Paper 42) (precedential). 

PGR Petitioners Will Likely Be Estopped From Raising Invalidity Arguments in Subsequent PTO Proceeding, Civil Actions, or ITC Proceedings

While three of the four PGR Final Written Decisions to date have resulted in the invalidation of the challenged claims, potential PGR petitioners must consider the risk of estoppel in subsequent proceedings. Title 35, Section 325(e) provides that the petitioner, the real party in interest, or privy of the petitioner may not assert in a later PTO proceeding, civil action, or ITC proceeding that any claim subject to a Final Written Decision is invalid on any grounds that the petitioner raised or reasonably could have raised during the PGR.31 Estoppel is only triggered by a Final Written Decision,32 meaning that if the Board denies institution or if the parties settle, the petitioner is not estopped from later pursuing challenges to the claims in subsequent proceedings. In addition, estoppel is applied on a claim-by-claim basis, so the petitioner will not be estopped from arguing in later proceedings that any previously unchallenged claims are invalid.33

The risk of estoppel is significantly greater for PGRs than IPRs, and calls into question whether seeking PGR review is prudent. While the substantive language of the estoppel statute for IPRs is the same as the provision for PGRs, the scope of any estoppel in a PGR that reaches Final Written Decision will be much broader since many more challenges can be brought in a PGR compared to an IPR. As discussed, IPR petitioners are limited to challenging claims as being anticipated or rendered obvious by patents or printed publications. Any estoppel triggered by a Final Written Decision will not preclude IPR petitioners from later challenging the claims based on grounds not available in IPR. Thus, any IPR resulting in a Final Written Decision where claims are not cancelled will not preclude a future challenge based on subject matter eligibility, indefiniteness, written description, enablement, or challenges based on prior art that is not a patent or printed publication.34 By contrast, PGR petitioners who receive an adverse Final Written Decision will almost certainly be estopped from later arguing invalidity on these grounds because most of them almost certainly reasonably could have been raised in the petition, the only significant exception being prior art systems subject to an on-sale bar that a petitioner might only learn about during district court discovery. In short, PGR petitioners should be prepared to live with the outcome of the PGR and should expect that they will probably not be able to make any further invalidity arguments once a Final Written Decision issues.

Another factor that should be considered before seeking PGR review is that CBMs have the least restrictive estoppel provisions. Like IPRs and PGRs, CBM petitioners are estopped from asserting in a subsequent PTO proceeding that the claim is invalid on any ground that a petitioner raised or reasonably could have raised. However, unlike PGR and IPR proceedings, CBM petitioners are only estopped from asserting in later civil actions and ITC proceedings that the challenged claim is invalid based on grounds that a petitioner actually raised during the prior CBM.35

Given all this, potential PGR petitioners should seriously consider whether a PGR is the best strategy for challenging validity. Because PGRs have significantly more draconian estoppel possibilities, potential petitioners should consider whether they should wait out the nine month window for filing a PGR petition and instead file either an IPR petition or, if available, a CBM petition.36 For example, if you are considering challenging a patent using printed publications as your prior art but are also aware of a prior art system that affects the validity of the claims, the potential estoppel should have you seriously considering whether to wait for the nine-month PGR window to close so you can file either an IPR or CBM instead of a PGR. Should a PGR challenge based solely on the printed publication prior art result in a Final Written Decision that does not cancel all the challenged claims, a petitioner will almost certainly be estopped from challenging the claims based on the system prior art in any future proceeding. Of course, a petitioner could also include challenges based on the system prior art in the PGR petition, but the American Simmental cases demonstrate the difficulties of relying on system prior art during PTAB contested proceedings. Thus, a petitioner in this situation should seriously consider waiting to file an IPR or a CBM petition.

In sum, a party filing a PGR petition is almost certainly limiting themselves to whichever challenges they raise, since if trial is instituted, any other challenge that might have been available to them in subsequent proceedings is likely going to be foreclosed by statutory estoppel.


As more PGR-eligible patents issue, parties who want to challenge the validity of the claims of those patents will be faced with whether to seek PGR review. While potential petitioners can challenge patents on a wide variety of grounds in a PGR, they must consider that estoppel following an unsuccessful PGR will also be very broad. Potential petitioners will have to be very confident in the challenges they bring in a PGR to overcome the very real fear of estoppel. It remains to be seen whether this fear of estoppel will undermine widespread use of PGR proceedings as more PGR-eligible patents are granted. 

  1. 35 U.S.C. § 321(b).

  2. Section 6(f) of the AIA provides that PGR is only available to patents that are subject to the first-inventor-to-file provisions. According to Section 3(n)(1), the first-inventor-to-file provisions “shall apply to any application for patent, and to any patent issuing thereon, that contains or contained at any time a claim to a claimed invention that has an effective filing date . . . that is on or after” March 16, 2013.

  3. DOCKET NAVIGATOR (last visited Nov. 17, 2016) (searching for “Post Grant Review” under type of pleading and summarizing the results under “PTAB Institutions”).

  4. See 157 CONG. REC. H4428 (daily ed. June 22, 2011) (statement of Rep. Manzullo) (“This bill would finalize the shift towards a European-style patent system through changing from a ‘first-to-invent’ to ‘first-to-file’ system; establishing a new set of ‘prior use’ rights; and adopting a third Europeanstyle ‘post-grant’ challenge.”).

  5. Annual Report 2015: Searches, Examinations, Oppositions, EPO (last visited Nov. 5, 2016).

  6. Patent Trial and Appeal Board Statistics, USPTO at 4 (Sept. 30, 2016); DOCKET NAVIGATOR (last visited Nov. 17, 2016) (searching for “Post Grant Review” under type of pleading).

  7. 35 U.S.C. § 311(b).

  8. DOCKET NAVIGATOR (last visited Nov. 17, 2016) (searching for “Post Grant Review” under type of pleading and summarizing the results under “PTAB Institutions”).

  9. Id. The calculations in the table take into account when claims are challenged on multiple grounds.

  10. Id.

  11. Id. at 25.

  12. Id. at 17.

  13. Id. at 15.

  14. Id. at 17.

  15. Id. at 18.

  16. Netsirv v. Boxbee, Inc., PGR2015-00009 at 2 (PTAB Aug. 2, 2016) (Paper No. 20).

  17. Id. at 9.

  18. Id. at 17.

  19. The holdings regarding corroboration are equally applicable to IPR and CBM proceedings.

  20. Am. Simmental II, PGR2015-00005 at 24-25.

  21. Id. at 26-27.

  22. Am. Simmental I, PGR2015-00003 at 22-23.

  23. Altaire Pharms., Inc. v. Paragon Bioteck, Inc., PGR2015-00011 at 7-9 (PTAB Nov. 14, 2016) (Paper No. 48).

  24. Id. at 14-17.

  25. Id. at 20.

  26. 35 U.S.C. § 326(d).

  27. Am. Simmental II, PGR2015-00005 at 42.

  28. Motions to amend have rarely been successful in IPR and CBM proceedings. According to the USPTO’s recently published study of motions to amend filed since the inception of the America Invents Act, “the Board has decided the merits of a motion to amend to substitute claims in only a fraction (118 trials, or 8 percent) of the 1539 completed AIA trials.” Patent Trial and Appeal Board Motion to Amend Study, USPTO at 3 (Apr. 30, 2016). Of the 118 motions to amend decided on the merits, only two were granted, four were granted in part, and 112 were denied. The judges denied or denied in part the motion to amend based on a specific statutory ground for patentability in 94 of the 116 trials (81 percent), and denied the motion based solely on procedural defect in the remaining 22 of the 116 trials (19 percent). Id. at 4, 6.

  29. Am. Simmental II, PGR 2015-00005 at 42-49.

  30. Am. Simmental I, PGR 2015-00003 at 37-39.

  31. 35 U.S.C. § 325(e).

  32. Id.

  33. See Westlake Servs., LLC v. Credit Acceptance Corp., CBM2014-00176 at 5 (PTAB May 14, 2015) (Paper No. 28).

  34. See Star Envirotech, Inc. v. Redline Detection, LLC, No. 8:12-cv-01861, 4-5 (C.D. Cal. Jan. 29, 2015) (order denying the plaintiff’s motion to strike the defendants’ invalidity contentions) (holding that the defendants were not estopped from relying on a reference that was a machine in the district court litigation because the reference was neither a patent or printed publication and therefore could not have been raised in the prior IPR).

  35. AIA § 18(a)(1)(D).

  36. Section 18(d) of the AIA defines “covered business method patent” as a patent that claims “a method or corresponding apparatus for performing data processing or other operations used in the practice, administration, or management of a financial product or service, except that the term does not include patents for technological inventions.”

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