Post-Grant Review (PGR) is one route to challenge a granted patent under the America Invents Act (AIA).  Unlike the AIA’s other route for challenging granted patents, inter partes review, which allows for challenges to any granted patent,  PGR can only be used to challenge patents filed under the first-to-file provisions of the AIA.   Generally speaking, this means that PGR is available to challenge patents filed on or after March 16, 2013.  However, because many such patents are still being prosecuted, or claim priority to an earlier patent, PGR has yet to become a well-utilized tool for challenging patent validity.

The requirement that the patent be filed under the first-to-file provisions is an aspect of petitioner standing.  That is, the petitioner in a PGR does not have standing to bring a PGR challenge unless the patent at issue is eligible for such review.  The question of standing is evaluated at the institution stage, and failure to establish standing will likely result in the merits of a challenge never being considered.  Nonetheless, the existence of a priority claim dating to before March 16, 2013 is not necessarily fatal to bringing a PGR.  A petitioner can challenge such a patent in a PGR by challenging the patent owner’s claim to that priority date, thereby establishing standing.

Establishing Eligibility for Post-Grant Review

A patent is considered to be filed under the first-to-file provisions if any claim in the patent is not entitled to a pre-AIA priority date.  This can occur, for example, if the disclosure of the priority document lacks sufficient written description to support a claim or fails to enable the claimed subject matter.  This analysis does not only look to granted claims.  In fact, a patent is considered filed under the first-to-file provisions of the AIA, and therefore subject to PGR, if any claim pending at any time during the application cannot claim the benefit of a priority date before March 16, 2013.  A petitioner can therefore establish entitlement to challenge a patent using PGR even if that patent is seemingly filed under pre-AIA laws by challenging the priority date of any granted or previously-pending claim.

The Patent Trial and Appeal Board (PTAB) has recently provided guidance on this opportunity to challenge priority claims during PGR.  In Inguran v. Premium Genetics   the challenged patent granted from a continuation application and claimed priority to several provisional and non-provisional applications filed prior to 2013.  Thus, it was seemingly ineligible for PGR.  Nonetheless, the petitioner argued that the claims of the granted patent lacked support in the disclosure of both the parents and the continuation, and for this reason the patent’s effective filing date was after March 16, 2013.

The PTAB decided to institute the PGR.  In doing so, the Board underscored two important factors.  First, while the Board found that the first independent claim in the patent was entitled to its claim of priority, the Board instituted PGR as to the entire patent because the Board found that the second independent claim was not entitled to a pre-AIA priority date.   This analysis affirms that a petitioner need only point to a single claim in the patent or application that cannot claim priority to a pre-AIA application to successfully institute a PGR.  As in Inguran, a petitioner can rely on a subset or a single granted claim that does not receive the benefit of the pre-AIA priority date.  Additionally, a petitioner would be wise to scour the prosecution history for any cancelled or amended claims that may not be sufficiently supported by the prior-filed applications to be entitled to the claim of pre-AIA priority.

Second, the PTAB clarified that the question of priority will be considered at the institution stage, because it bears on the petitioner’s standing to request and institute the PGR.  In promulgating rules governing PGR, the USPTO noted that it is the petitioner’s burden to certify the grounds for standing in the petition.   In Inguran, the Board confirmed that the effective filing date of the patent is a threshold issue that will be determined at the institution stage.

Proving Standing at the Institution Stage

The fact that standing must be established at the institution stage has important ramifications for a petitioner wishing to challenge the priority claim of a patent using PGR.  In particular, it means that the petitioner must establish any and all priority defects in the initial petition.  Petitions for PGR are subject to strict page limits.  Due to this restriction, a petitioner who must establish an invalid priority claim is somewhat handicapped in the petition.  While a petitioner who does not need to challenge the priority claim can simply provide a certification stating the grounds for standing, a petitioner challenging a priority claim must establish entitlement to bring the PGR as well as present the normal invalidity arguments.  The petition must clearly set forth the defect in the priority claim in order to establish standing and must also provide convincing arguments that it is “more likely than not” that at least one patent claim is invalid.   If the petitioner fails to establish standing, the Board will not reach the merits of the invalidity arguments.  Therefore, the petitioner must convincingly establish standing while reserving sufficient space in the petition to persuade the Board that their invalidity arguments are likely to succeed.

Drafting a convincing petition is particularly high stakes for the petitioner given that the Federal Circuit has repeatedly confirmed that decisions to not institute review are nonappealable.   Thus, a petitioner who fails to convince the PTAB of the priority defect (or the likelihood that a claim of a patent is invalid) may be unable to challenge the Board’s determination through appeal.

In light of these concerns, a petitioner must carefully balance the arguments in the initial petition.  In particular, a petitioner should strategically identify the patent claims having the weakest priority claims, and should consider whether to challenge the granted claims or a claim that was pending during prosecution, or both, depending on page restrictions.  The petitioner should bear in mind that establishing standing is a threshold determination, without which the Board will not even reach the merits of the petition.

Considerations for Patent Owners

Patent owners need also be aware of the ramifications of challenges to their priority dates during PGR.  Although the petitioner bears the burden of establishing standing, because standing will be evaluated at the institution stage, a prudent patent owner should consider filing a preliminary response to challenge the petitioner’s standing.  Although the patent owner can challenge standing issues later in a PGR, for example, at trial or in a patent owner response,  it can be more expedient to put a stop to the PGR at the institution stage.  Successfully rebutting petitioner standing can mean that the PTAB never moves on to the merits of the invalidity challenge, thus reducing the risk that the Board questions the strength of the patent.

Patent owners should also bear in mind that they cannot rely on any presumption of entitlement to the claimed priority date.  Although the USPTO notes the effective filing date during prosecution, the priority claim is typically not examined, and therefore is not entitled to any presumption of correctness or entitlement.   As a result, priority claims may be vulnerable to attack and patent owners should not allow the petitioner’s challenge to go unanswered.


As more patents filed under the first-to-file provisions are granted, there will likely be an uptick in PGR proceedings.  However, in the meantime, petitioners can challenge patents claiming pre-AIA priority in a PGR by challenging the claim to priority.  PGR can be a more flexible and powerful tool than inter partes review, partly because it is available immediately upon the grant of the patent and partly because any ground of invalidity can be raised during PGR.   Petitioners wishing to use PGR must make their case for standing in the initial petition by challenging the priority claim of the patent.  In this way, petitioners can bring seemingly immune patents within the purview of PGR.