IPR tricks of the trade: the tough task of 'swearing behind' an asserted prior art reference

The United States Patent and Trademark Office (USPTO) is seen in Alexandria, Virginia
The United States Patent and Trademark Office in Alexandria, Virginia, U.S. REUTERS/Andrew Kelly

November 26, 2021 - A third party who is not the patent owner may file a petition for inter partes review (IPR) to challenge the validity of an issued patent. A petitioner may challenge a patent's claims on the basis of prior art consisting of patents or printed publications. 35 U.S.C. § 311(b). IPRs are frequently filed as part of a defense strategy to challenge the validity of an asserted patent.

The America Invents Act (AIA) transitioned U.S. patent law from a first-to-invent system to a first-to-file system. While patents that issue today are mostly AIA patents (i.e., first-to-file), many pre-AIA patents are still being litigated and are subject to IPR petitions. A patent is considered a pre-AIA patent if it has an effective filing date before March 16, 2013.

In IPRs, the owner of a pre-AIA patent may attempt to "antedate" or "swear behind" an asserted reference by proving a date of invention before the critical date of the reference. If the patent owner is successful in antedating the reference, the patent owner would remove that reference as prior art against the challenged patent.

A patent owner can demonstrate prior invention for a pre-AIA patent in one of two ways: (1) establish an earlier reduction to practice of the claimed invention before the critical date of the reference, or (2) establish conception of the invention prior to the critical date plus reasonably continuous diligence to reduce the invention to practice after the critical date. REG Synthetic Fuels, LLC v. Neste Oil Oyj, 841 F.3d 954, 958 (Fed. Cir. 2016); Perfect Surgical Techniques, Inc. v. Olympus Am., Inc., 841 F.3d 1004, 1009 (Fed. Cir. 2019)(a patent owner "must show there was reasonably continuous diligence.").

A patent owner "bears the burden of establishing that its claimed invention is entitled to an earlier priority date than an asserted prior art reference." In re Magnum Oil Tools Int'l Ltd., 829 F.3d 1364, 1375-76 (Fed. Cir. 2016). Thus, it is the patent owner who has the burden to prove that it is entitled to an earlier date of invention.

A reduction to practice can either be a constructive reduction to practice, which occurs when a patent application is filed, or an actual reduction to practice, such as when the inventor makes a prototype or working model of the invention.

An actual reduction to practice requires:

(1) construction of an embodiment or performance of a process that meets all the limitations of the claims at issue,

(2) a determination that the invention would work for its intended purpose, and

(3) sufficient evidence to corroborate inventor testimony regarding these events. Medichem, S.A. v. Rolabo, S. L., 437 F.3d 1157, 1169 (Fed. Cir. 2006).

Conception must encompass all the limitations of the claims at issue and is the formation of "a definite and permanent idea of the complete and operative invention." Kolcraft Enters., Inc. v. Graco Children's Prods., Inc., 927 F.3d 1320, 1324 (Fed. Cir. 2019). Conception and reduction to practice require a contemporaneous recognition of the invention represented in the claims — conception and reduction to practice cannot be established after the fact. Mycogen Plant Sci. v. Monsanto Co., 243 F.3d 1316, 1335 (Fed. Cir. 2001).

Independent corroboration of evidence is required for both conception and reduction to practice. An inventor's testimony may not corroborate unwitnessed evidence of the inventor, and the "testimony of one co-inventor cannot be used to help corroborate the testimony of another [inventor]." Medichem, 437 F.3d at 1171. Inventor-generated documents are not independent information and cannot corroborate inventor testimony. Kolcraft, 927 F.3d at 1324.

One reason for the independent corroboration requirement is that an inventor may "be tempted to remember facts favorable to their case by the lure of protecting their patent or defeating another's patent." Mahurkar v. C.R. Bard, Inc., 79 F.3d 1572, 1577 (Fed. Cir. 1996).

These evidentiary burdens often prove difficult for patent owners seeking to "swear behind" an asserted reference. For example, in Cienna Corp. v. Capella Photonics, Inc., IPR2021-000624, Paper 20 (Nov. 16, 2021), the Patent Trial and Appeal Board granted institution of an IPR over the patent owner's arguments that it conceived of the invention before the critical date of an asserted reference and subsequently reduced the invention to practice. The Board found that patent owner's conception evidence did not show that the inventors conceived of all the limitations in the challenged claims, and that the conception evidence was not sufficiently corroborated by non-inventor testimony.

In Apple Inc. v. Yu, IPR2019-01258, Paper 29 (Jan. 5, 2021), the Board found that the patent owner's conception and reduction to practice evidence was insufficiently corroborated because the patent owner provided only inventor testimony to support its argument that the inventors conceived of the invention and subsequently reduced it to practice.

While the evidentiary burden is high for patent owners to swear behind an asserted reference, some patent owners have succeeded in doing so before the Board. For example, in Green Cross Corp. v. Shire Human Genetic Therapies Inc., Paper 89 (Mar. 22, 2017), the patent owner successfully established an actual reduction to practice before the critical date of an asserted reference, supported by laboratory evidence, inventor testimony, and declarations from three non-inventor employees of the patent owner to corroborate the inventor's testimony.

Similarly, in Lectrosonic, Inc. v. Zaxcom, Inc., IPR2018-00972, Paper 41 (Nov. 7, 2019), the patent owner successfully established an earlier conception of the invention recited in the challenged claims prior to the critical date of the reference, coupled with diligence in constructively reducing the invention to practice in the form of a patent application. The Board credited draft patent applications and communications with the patent attorney as corroborating the inventors' testimony that they conceived of the limitations recited in the claims.

Patent owners seeking to overcome an IPR challenge against a pre-AIA patent may consider swearing behind an asserted reference. Patent owners have to meet the evidentiary requirements identified above. The Board has shown that it is receptive to this evidence, provided that it addresses all claim limitations and is independently corroborated.

This article reflects only the present personal considerations, opinions, and/or views of the authors, which should not be attributed to any of the authors' current or prior law firm(s) or former or present clients.

Opinions expressed are those of the author. They do not reflect the views of Reuters News, which, under the Trust Principles, is committed to integrity, independence, and freedom from bias. Westlaw Today is owned by Thomson Reuters and operates independently of Reuters News.

David McCombs is a partner in the Dallas office of Haynes Boone and serves as primary counsel for leading corporations in inter partes review. He can be reached at david.mccombs@haynesboone.com.

Eugene Goryunov is a partner in the intellectual property practice group in the Chicago office of the firm and an experienced trial lawyer who represents clients in complex patent matters involving diverse technologies. He can be reached at eugene.goryunov@haynesboone.com.

Jonathan Bowser is of counsel in the firm's Washington, D.C., office and focuses his practice on patent litigation disputes before the Patent Trial and Appeal Board and federal district courts. He can be reached at jonathan.bowser@haynesboone.com.