Federal Circuit Clarifies Requirements for Prior Art Under Pre-AIA 35 U.S.C. § 102(e)

Knowing what qualifies as prior art is a core requirement of patent practitioners—whether in life sciences, in the technology sectors or in post-grant proceedings. It is important to keep abreast of changes to the rules, especially if the Federal Circuit weighs in. On March 24, 2025, the Federal Circuit issued a precedential decision in In Re Riggs, Case No: 22-1945 (Fed. Cir. Mar. 24, 2025) clarifying the standard for determining whether a published patent application can be considered prior art as of its provisional filing date. Although this case was decided under pre-AIA law, the standard elucidated by the Federal Circuit reinforces the importance of drafting detailed provisional applications and knowing the requirements for establishing prior art under both pre-AIA and AIA law.

Pre-AIA 35 U.S.C. § 102(e) and AIA 35 U.S.C. § 102(a)(2) deal with what many in the field refer to as “submarining prior art.” Even when armed with a bullet-proof prosecution strategy, “submarining prior art” can still take patent applicants and inventors by surprise. “Submarining prior art” is based on the principle that a patent application remains “secret” for typically 18 months from its filing date, until the USPTO publishes the patent application or the corresponding patent. During this period of “secrecy,” a competing inventor is unaware of the existence of the unpublished, pending patent application (hence the term, “submarining prior art”). As such, the inventor may prepare and file a patent application directed to what he or she believes is a patentable invention but that happens to cover the same or similar technology as that disclosed in the earlier-filed, as-yet-unpublished patent application. Only after the earlier-filed patent application publishes (like a submarine surfacing from underwater) does it become prior art as of its filing date. As one could imagine, this is potentially problematic for the competing inventor; the earlier-filed, now-published patent application might be prior art to the inventor’s later-filed patent application. In Re Riggs addresses when a patent or patent application qualifies as prior art under this type of situation.

The Riggs patent application—U.S. Patent Application No. 11/005,678 (hereafter, “the ’678 application”)—had a priority date of July 28, 2000. During prosecution, the Examiner rejected the ’678 application under pre-AIA § 102(e) as anticipated by a patent publication, Lettich et al. (hereafter, “Lettich”). Lettich was filed on April 26, 2001 and claimed priority to a provisional application filed on April 27, 2000. In order to qualify as prior art under § 102(e), Lettich needed to be entitled to its April 27, 2000 priority date, which pre-dated the ’678 application’s July 28, 2000 priority date. Riggs addressed whether Lettich is entitled to the April 27, 2000 filing date of its provisional application for the purposes of qualifying as prior art to the ’678 application under § 102(e).

The Examiner and the Patent Trial and Appeal Board (PTAB) relied on Dynamic Drinkware[1], Amgen[2], and MPEP § 2136.03 in determining whether Lettich qualifies as prior art under § 102(e). Specifically, they considered whether Lettich’s provisional application provided written description support for at least one claim in Lettich. Without any such written description support in the provisional, Lettich’s priority date for the purposes of 35 U.S.C. § 102(e) would be the April 26, 2001 non-provisional filing date, which would be insufficient to render Lettich prior art to the ‘678 application. The PTAB found that Lettich satisfied the aforementioned written description test identifying support in the provisional application for each limitation of claim 1 in Lettich. The PTAB concluded on this basis that Lettich was available as prior art under 35 U.S.C. § 102(e).

The Federal Circuit agreed with the PTAB “that a prior art patent or published application cannot be accorded the benefit of its provisional application’s filing date absent a showing that the provisional application provides support for a claim of the patent or published application”[3] However, the Federal Circuit held that this finding alone is insufficient to determine whether a patent or published application qualifies as prior art under § 102(e).[4] As a second step of the analysis, “the provisional application must also provide written description support for the specific portions of the patent specification identified and relied on in the prior art rejection.”[5] The Federal Circuit noted that neither Dynamic Drinkware nor Amgen addressed the problem at issue here, as the appellants in those cases failed to satisfy the initial requirement that the provisional provide support for at least one claim. As such, there was no need in those cases to address the subsequent question of whether the specific text in the patent document relied on by the Examiner in the rejection also had written description support in the provisional application.

The Federal Circuit clarified that even if a provisional application provides written description support for at least one claim of the patent document cited in a rejection, the provisional application must also provide written description support for the specific portions of the specification identified and relied on by the Examiner in the rejection. As the Federal Circuit reasoned, “[i]t makes no sense to suggest that if a single claim is supported by the provisional application, then everything in the later filed application gets the benefit of the provisional date whether supported or not.”[6] The Federal Circuit vacated and remanded the PTAB’s decision because the PTAB did not address the second step of the analysis.

The Riggs decision aligns with MPEP § 2136.03 (III). It explains that two elements must be satisfied in order for a published patent application or patent to have the benefit of its provisional filing date under § 102(e):

[A]t least one of the claims in the reference patent, patent application publication, or international application publication is supported by the written description of the provisional application in compliance with pre-AIA 35 U.S.C. 112, first paragraph, or 35 U.S.C. 112(a) . . . [and] . . . [t]he provisional application must also describe, in compliance with pre-AIA 35 U.S.C. 112, first paragraph, or 35 U.S.C. 112(a), the subject matter relied upon in the reference patent or publication to make the rejection.[7]

When it comes to AIA law, the MPEP, like that for pre-AIA law, requires that a provisional application to which a reference patent document claims a right of priority “describe[] the subject matter” relied upon in the reference patent document in a prior art rejection.[8] Although Riggs is applicable only to pre-AIA law, given the related guidance in the MPEP regarding the treatment of prior art under pre-AIA 35 U.S.C. § 102(e) and AIA 35 U.S.C. § 102(a)(2), as well as the Federal Circuit’s stated rationale in its decision, one may reasonably expect that a similar outcome may apply in the AIA context too.

What does all of this mean for patent practitioners going forward?

As the Federal Circuit emphasized, “it is best to treat a published provisional application—like a published non-provisional application or patent—as prior art for all that it teaches as of its filing date.”[9] Taking this into account, patent practitioners should draft provisional applications with as complete a disclosure as possible. A cursory provisional application may be necessary when circumstances do not permit a more fulsome drafting process. However, filing a fully fleshed-out provisional application will have benefits not only in ensuring entitlement to an earlier priority date for the eventual non-provisional filing, but also in ensuring entitlement to the earliest priority date for the purposes of qualifying as prior art against later patent applicants.

Although In Re Riggs has not made it any easier to predict “submarining prior art,” it has provided additional means for patent applicants and patent owners in post-grant proceedings to challenge the availability of a patent or patent publication as prior art as of its provisional filing date. Indeed, while “submarining prior art” may still bring an element of surprise, patent practitioners now have more tools in their arsenal when confronting such art during prosecution and post-grant proceedings.

[1] Dynamic Drinkware, LLC v. National Graphics, Inc., 800 F.3d 1375 (Fed. Cir. 2015).

[2] Amgen Inc. v. Sanofi, 872 F.3d 1367 (Fed. Cir. 2017).

[3] In Re Riggs, Case No: 22-1945, 12 (Fed. Cir. Mar. 24, 2025).

[4] Id.

[5] Id.

[6] Id.

[7] MPEP § 2136.03, supra, note 3.

[8] MPEP § 2154.01(b).

[9] In Re Riggs, supra, at 13.