The PTAB has broad discretion under 35 U.S.C. § 325(d) to deny institution if “the same or substantially the same prior art or arguments previously were presented to the Office.” Several are aware that the PTAB commonly exercises its discretion to deny “follow-on” petitions that seek to challenge the validity of a patent that has already been the subject of an inter partes review proceeding. However, it is important to know what the PTAB considers when deciding whether to deny institution under section 325(d).

When evaluating whether to exercise discretion, when the same or substantially the same prior art or arguments previously were presented to the Office under section 325(d), the PTAB has weighed common factors, such as:

(a) the similarities and material differences between the asserted art and the prior art involved during examination; (b) the cumulative nature of the asserted art and the prior art  evaluated during examination; (c) the extent to which the asserted art was evaluated during examination, including whether the prior art was the basis for rejection; (d) the extent of the overlap between the arguments made during examination and the manner in which Petitioner relies on the prior art or Patent Owner distinguishes the prior art; (e) whether Petitioner has pointed out sufficiently how the Examiner erred in its evaluation of the asserted prior art; and (f) the extent to which additional evidence and facts presented in the Petition warrant reconsideration of the prior art or arguments.

See Becton, Dickinson & Co. v. B. Braun Melsungen AG, Case IPR2017-01586, slip op. at 17–88 (PTAB Dec.15, 2017) (Paper 8) (informative). However, this list is non-exclusive and is not considered by every panel. Rather, the analysis is fairly fact specific. The PTAB will also weigh “petitioners’ desires to be heard against the interests of patent owners, who seek to avoid harassment.” Agrinomix, LLC v. Mitchell Ellis Prods., Inc., Case No. IPR2017-00525, slip op. at 11 (PTAB June 14, 2017)(Paper 6)(denying institution where the prior art reference “was discussed in the Specification of the ’583 patent, was cited by the applicant in an information disclosure statement, and was relied upon by the Examiner in an office action to reject certain limitations of the dependent claims[.]”).

Although the analysis is done on a case-by-case basis, there are some common trends amongst the PTAB’s recent decisions.

When Prior Art is Specifically Relied on During Prosecution

Generally, the PTAB will exercise discretion to deny institution when the prior art cited in the Petition was specifically relied on and substantively considered by the Examiner. For example, in Dorco Co., Ltd. v. The Gillette Co., LLC, Case No. IPR2017-00500, slip op. at 15 (PTAB June 21, 2017) (Paper 7), the PTAB exercised its discretion under section 325(d) and denied institution because it determined that the petitioner’s grounds I and II presented essentially the same question of patentability as previously considered by the Examiner. Although the prior art references were not exactly the same, the PTAB held that the reference substituted by the petitioner is an example of the reference cited by the Examiner and disclosed the same feature. See id. at 16. The PTAB determined that the petitioner’s ground II identified no claim elements disclosed by the substituted prior art reference that were not also disclosed by the art cited by the Examiner during prosecution. See id. at 16.

Similarly, in CSL Behring GMBH v. Shire Viropharma Inc., Case No. IPR2017-01512, slip op. at 13-14(PTAB Dec. 7, 2017) (Paper 12), the PTAB denied institution under section 325(d) and found that the petitioner made essentially the same arguments as to obviousness that the Examiner already considered. The PTAB held that “the prosecution history demonstrates that the Examiner considered many of the same issues with respect to the Schranz Declaration as Petitioner is arguing here” and that although “the Examiner noted in allowing the claims that Applicant Shire had established the secondary consideration of long-felt need and failure of others, the Examiner also stated that the art did not suggest the claimed dosage.” Id. at 14.

However, when the prior art was not specifically considered by the Examiner during prosecution, the PTAB has generally granted institution. See Pure Storage, Inc. v. Realtime Data LLC, Case No. IPR2018-00549, slip op. at 11 (PTAB July 23, 2018) (Paper 7) (noting that “there is no evidence of record that [the prior art references] were substantively considered by the Examiner.”). For example, in Synaptic Medical Inc. v. Karl Storz-Endoscopy-America, Inc., Case No. IPR2018-00462, slip op. at 10 (PTAB July 16, 2018) (Paper 6), the PTAB declined to exercise discretion to deny institution, concluding that “the references here were not applied to reject the claims of the ’360 Patent and there is no evidence that the Examiner considered the particular disclosures cited in the Petition or addressed arguments similar to those Petitioner now presents.” Additionally, when the prior art was merely cited in an Information Disclosure Statement, this was generally not enough for the PTAB to deny institution. See Comcast Cable Communs., LLC v. Promptu Sys. Corp., Case No. IPR2018-00342, slip op. at 17 (PTAB July 19, 2018) (Paper 13)(granting institution “[b]ecause the claims of the ’326 patent were substantially modified during the reissue prosecution and because [the prior art] was only cited in an IDS and not applied by the examiner in the reissue application process in any rejection of claims”). The prior art must be specifically relied on by the Examiner.

When Same Prior Art is Relied on but Not the Same Combination

One issue commonly before the PTAB is when the primary prior art references where considered by the Examiner during prosecution, but the petition makes an obviousness argument where the references are presented in combination with others that were not considered. There does not appear to be a consensus at the PTAB of whether discretion should be exercised under section 325(d) and for now appears to be highly fact dependent.

The PTAB has denied institution where the main prior art references in the Petition were the same as those considered by the Examiner, even though the petitioner used the references in different combinations. For example, in Microsoft Corp. v. Koninkijke Philips N.V., Case No. IPR2018-00277, slip op. at 11 (PTAB June 8, 2018)(Paper 10), the PTAB denied institution, finding the secondary prior art references to be cumulative to those relied on during prosecution even though the “Petitioner’s asserted grounds and the Examiner’s proposed combinations involving Traw and Kaliski rely on different primary references, or that Petitioner’s asserted grounds rely on two references whereas the Examiner’s proposed combinations involving Traw and Kaliski rely on four or more references.” Similarly, in Pfizer, Inc. v. Genentech Inc., Case No. IPR2018-00373, slip op. at 14 (PTAB Aug. 2, 2018)(Paper 12), the PTAB denied institution where “during prosecution of the challenged claims, the Examiner considered Kabbinavar with respect to anticipation and obviousness, and also considered Chen with respect to obviousness” and “the Petition relies upon those same references to support anticipation and obviousness grounds.”

However, by contrast, the PTAB has granted institution where the main prior art references were the same but the combinations differed. For example, in St Jude Medical, LLC v. Snyders Heart Valve LLC, Case No. IPR2018-00105, slip op. at 12 (PTAB May 3, 2018) (Paper 15), the PTAB concluded that “[t]he evidence of record does not demonstrate that the Examiner considered the references in the combinations relied upon by Petitioner or addressed arguments similar to those Petitioner now presents before the PTAB as the basis for the unpatentability of the challenged claims.” Similarly, in Trans Ova Genetics, LC. V. XY, LLC, Case No. IPR2018-00250, slip op. at 18 (PTAB June 27, 2018)(Paper 9), the PTAB granted institution and concluded that “the Petition presents a substantially different argument than was articulated by the Examiner and that the Examiner’s failure to appreciate the full scope of Lu’s disclosure warrants reconsideration of the asserted prior art.”

Additionally, where the petition includes new or additional evidence not considered by the Examiner, the PTAB may grant institution. See Sanofi-Aventis U.S. LLC v. Immunex Corp., Case No. IPR2017-01884, slip op. at 12 (PTAB Feb. 15, 2018)(Paper 14) (finding that “because the Examiner did not have the benefit of Petitioner’s additional experimental evidence relating to competition, we are not persuaded that the same or substantially the same prior art or arguments were previously presented to the Office.”).


Section 325(d) provides the PTAB with a great deal of leeway when determining whether to exercise discretion to deny institution. However, the PTAB’s recent decisions provide key takeaways for patent owners and petitioners when dealing with section 325(d). For patent owners, the decisions demonstrate that to make a successful argument for denial under this section, the prior art must have been considered by the Examiner during prosecution. A patent owner cannot merely rely on the fact that the prior art was cited by the Examiner or cited in an Information Disclosure Statement. The patent owner should, where applicable, demonstrate that the reference was substantively relied on.

As for petitioners, the decisions demonstrate the importance of careful selection of the prior art references when challenging validity. The best strategy for avoiding section 325(d) is to rely on new art. However, if new art is not available, it is important to examine the prosecution history closely and see which prior art references were primarily considered. Even if a petitioner decides to use the same primary references, it is important to examine other secondary references that may be used that were not considered during prosecution.

Either way, the recent PTAB decisions demonstrate the prevalence of section 325(d) in institution decisions and as such, both patent owners and petitioners should keep it in mind when preparing their arguments before the PTAB.