Many patent applicants submit large Information Disclosure Statements (IDS) that contain all possible references of which the Applicant is aware. This is particularly common when several patent applications containing related subject matter are filed. One objective is to shield the Applicant from a charge of inequitable conduct for failure to submit a potentially material reference. Another objective is to bolster the presumption of validity by allowing the argument that a particular reference was considered by the Examiner during prosecution. Unfortunately, submitting a very large IDS may not accomplish either objective.
Examiners are frequently critical of large IDSs, and in some cases, suggest that the Applicant identify references in the IDSs that are particularly relevant or material. No response to that request, however, is required. In some patent challenges, opponents have accused the applicant of burying material prior art in large IDSs with the hopes that the Examiner will overlook it. Patent challengers also argue that an Examiner cannot realistically consider all of the cited references when they are included in such "mega-IDSs."
May 19, 2025 Order from the Acting Director of the USPTO:
Mega-IDSs were recently addressed in relation to the denial of a petition for inter partes review of U.S. Patent No. 11,925,202 B2. The denied petition relied exclusively on prior art references that were submitted by the Applicant and that were made of record by the Examiner during examination of the application. The IDS submitting the references contained over 1,000 references, which is more than 40 times larger than a typical IDS. The Examiner requested that the applicant identify any references to which the Examiner should pay particular attention, but the applicant did not respond to this request from the Examiner. Nevertheless, the Examiner made all of the references of record.
One of the reasons that the PTAB had initially denied institution of the petition is that the references asserted in the petition had been previously presented to the Examiner during examination of the application. Section 325(d) of the patent statute provides that the Director may deny institution when "the same or substantially the same prior art or arguments previously were presented to the Office." See Advanced Bionics, LLC v. MED-EL Elektromedizinische Geräte GmbH, IPR2019-01469, Paper 6 (PTAB Feb. 13, 2020) (precedential).
The petitioner then filed a request for Director Review of the Decision denying institution. In response to the request for Director Review, Acting Director Coke Morgan Stewart issued an order on May 19, 2025 "Granting Director Review, Vacating the Decision Denying Institution, and Remanding to the Board for Further Proceedings." The Order remanded the case back to the PTAB, because inclusion of the applied references in such a large IDS may provide evidence and facts that warrant reconsideration of the prior art or arguments: "Thus, the Board should consider a petitioner's argument based on the volume of the references submitted to the Office during examination and any applicant information or assistance regarding the relevance of references." In other words, the Order acknowledges the potential for a patent examiner to overlook references that are submitted in very large IDSs, and raises some concern about the effectiveness of submitting large IDSs.
Impact of Large IDSs on Charges of Inequitable Conduct:
As mentioned above, many patent practitioners submit large IDSs, essentially submitting all references that might reasonably be material, in the hopes of avoiding a charge of inequitable conduct that might otherwise be raised by failing to submit an arguably material reference for the Examiner's consideration.
Potential inequitable conduct was at stake in Therasense v. Becton, 649 F.3d 1276 (Fed. Cir. 2011). Prior to Therasense, the doctrine of inequitable conduct had grown to include the mere nondisclosure of information to the PTO. In line with this wider scope, inequitable conduct later came to require a finding of both intent to deceive and materiality. Star Scientific Inc. v. R.J. Reynolds Tobacco Co., 537 F.3d 1357, 1365 (Fed. Cir. 2008). As recognized in the Therasense opinion, as a result of the threat of a charge of inequitable conduct, "patent prosecutors regularly bury PTO examiners with a deluge of prior art references, most of which have marginal value." A white paper by the American Bar Association concluded that "Applicants disclose too much prior art for the PTO to meaningfully consider, and do not explain its significance, all out of fear that to do otherwise risks a claim of inequitable conduct." ABA Section of Intellectual Property Law, A Section White Paper: Agenda for 21st Century Patent Reform 2 (2009).
In recognition of this problem, the Therasense Court held that "A finding that the misrepresentation or omission [of a material reference] amounts to gross negligence or negligence under a 'should have known' standard does not satisfy this intent requirement." Therasense at 1290. The Therasense Court recognized the issue of burying material references in large IDSs, hoping that tightening the test for the intent component would reduce the number of very large IDSs. The Court held that to prove inequitable conduct, "the accused infringer must prove by clear and convincing evidence that the applicant knew of the reference, knew that it was material, and made a deliberate decision to withhold it." Therasense at 1290.
How large an IDS must be before it can be construed as burying a reference must be determined on a case by case basis. In Illinois Tool Works, Inc. v. Termax LLC, No. 20 D 5416 (N.D. Ill., July 24, 2023), the court held that including a reference in a list of seven references did not amount to burying the reference. In Molins Plc v. Textron, Inc., 48 F.3d 1172 (Fed. Cir. 1995), the patent applicant submitted an IDS document that was 11 pages in length and contained a listing of 23 U.S. patents, 27 foreign patents, and 44 U.S. and foreign printed publications. In that case, the Court determined that a reference was not buried in the IDS.
In a 2023 (in a post Therasense case), Bridgestone Americas Tire Operations, LLC v. Speedways Tyres Limited et al., No. 4:22-cv-0145-P (N.D. Tex., Aug. 9, 2023), the Court stated that "hiding references in a sea of other references is not 'with[holding] or misrepresent[ing]' prior art references," and Speedways did "not provide any legal authority for the proposition that hiding material prior art references in a sea of other prior art references satisfies the 'intent to mislead' element." Thus, that court did not regard burying as a cognizable basis for inequitable conduct.
On the other hand, in the order on May 19, 2025 "Granting Director Review, Vacating the Decision Denying Institution, and Remanding to the Board for Further Proceedings", mentioned above, the Acting Director implied that the Examiner could not effectively consider all of the citations in an IDS listing over 1,000 references. Significantly, during the examination of U.S. Patent No. 11,925,202 B2, the Examiner specifically requested that the applicant identify references to "which the examiner should [pay] particular attention," and the applicant did not respond to that request. Such a refusal to respond is likely a factor that a court could consider when deciding on the issue of inequitable conduct when a large IDS is submitted.
Presumption of Validity:
Section 282 of the patent statute states that "A patent shall be presumed valid." It further states that "The burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity." In the 2010 Supreme Court decision in Microsoft Corp. v. i4i Limited Partnership, 564 US 91 (2010), the Court held that an invalidity defense needed to be proved by clear and convincing evidence. Id. at 97. However, the Court recognized that "new evidence supporting an invalidity defense may 'carry more weight' in an infringement action than evidence previously considered by the PTO". Id at 110. Accordingly, there is clearly a benefit to a patent applicant to ensure that the PTO has considered all possible material art during examination of the application.
When a patent applicant submits a large number of references to the PTO without disclosing which are most relevant to patentability, a court may conclude that the Examiner failed to consider all of them as relevant prior art, thereby dissipating the presumption of validity. Mooney v. Brunswick Corp., 663 F.2d 724, 212 U.S.P.Q. 401, 407 (7th Cir. 1981). In the Mooney case, the patent applicant cited 56 prior art references in no purported order of importance. The Court of Appeals found that:
Considering the large number of references which were included on the patent examiner's list, we do not think it unreasonable for the district court to have concluded that the examiner failed to consider these drawings as relevant prior art. As a result, the statutory presumption of validity which may be enhanced when prior art has been considered and rejected by the Patent Office is dissipated in Mooney's case with respect to the Kiekhaefer drawing and the Gale Products drawing.
Id at 407.
Thus, in the Mooney case, the Court found that references listed among 56 citations may not have been properly considered by the Examiner. This is an important finding when considering the presumption of validity and whether a reference or argument is cumulative for the purpose of an inter partes review petition.
Conclusions:
First and foremost, all material prior art should be submitted in a timely manner. Nothing in any of the decisions that are discussed herein diminishes the duty of candor that all participants in the patent process owe to the USPTO.
Second, submitting a very large IDS is better than failing to submit a potentially material reference. One balance that some practitioners use when filing a large IDS is to separately identify a small list of what are believed to be the most relevant or material references included in the large IDS. This must be done carefully, noting in the submission that this list contains what the Applicant believes to be the most relevant cited art. An explanation of the art is not necessary, unless the art is not in the English language. A practitioner should work with the Applicant to be sure that the list contains all of the art that the Applicant and its representatives understand to be the most relevant.
Third, when submitting a large IDS that is generated from art cited in a plurality of related or co-pending applications, an applicant might explain why the IDS is so large, so that the Examiner will have a better understanding as to the origin of the references. Including search reports and office actions from such co-pending applications may also be prudent to assist in focusing review of the submitted references.
Fourth, if the Examiner does ask to have the most relevant references identified, the applicant should comply, keeping in mind that any indications of relevance should be expressly based on the Applicant's understanding and belief as to the content of the references.
Fifth, if the IDS is becoming very large, consider omitting category A references, or at a minimum, separating the category A references from those that were cited as category X or Y references, e.g., in separate IDSs.
Sixth, consider omitting citation of cumulative subject matter, such as international counterparts to references already of record. This will help to limit the size of the IDS.
Seventh, if a determination is made not to include a reference in an IDS, it may be helpful to make a note to the file about why the reference was not included, e.g., because it was cumulative or not material.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
