The US Court of Appeals for the Federal Circuit affirmed a Patent Trial & Appeal Board decision that the patent owner successfully demonstrated that the claimed heart catheter invention was conceived and reduced to practice prior to the effective date of the reference, by record evidence of adequate testing to demonstrate that the invention would work for its intended purpose. Medtronic, Inc. v. Teleflex Innovations S.Á.R.L., Case Nos. 21-2356; -2358; -2361; -2363; -2365 (Fed. Cir. May 24, 2023) (Moore, C.J.; Lourie, J.) (Dyk, J., dissenting).

Teleflex Innovations owns five patents directed to guide extension catheters that use a tapered inner catheter that runs over a standard coronary guidewire to reduce the likelihood that a guide catheter will dislodge from the coronary artery’s opening. All of the patents are related and share a common specification. Around the time of the challenged patents’ priority date, the applicant was working to develop two commercial variants of similar technology: the “rapid exchange” (or RX) version of the GuideLiner product, which Teleflex claims practices the challenged patents, and an “over-the-wire” (or OTW) variant, which does not practice the challenged patents.

Medtronic petitioned for inter partes review (IPR), challenging all five patents on the basis that they were predated by a patent to Itou. During the IPR proceedings, Teleflex claimed that conception and reduction to practice occurred prior to Itou’s priority date and submitted several declarations and exhibits such as lab notebooks, internal company memoranda, presentations, invoices, sales orders, photographs, engineering drawings and documents from outside patent counsel in support of its contentions. Ultimately, the Board found that Itou did not constitute prior art and therefore Medtronic had failed to demonstrate that the challenged claims were unpatentable. Medtronic appealed.

On appeal, Medtronic did not challenge conception but argued that the Board’s findings on actual reduction to practice and reasonable diligence toward constructive reduction to practice should be reversed. To establish an actual reduction to practice, the patent owner must show that the inventors constructed an embodiment that met all the limitations of the claimed invention and determined that the invention would work for its intended purpose. Medtronic’s arguments were based on the grounds that the Board erred in three ways:

1. Incorrectly identifying the intended purpose of the claimed invention
2. Not requiring comparative testing to demonstrate that the invention worked for that purpose
3. Relying solely on uncorroborated inventor testimony.

On the first issue, Medtronic argued that the Board incorrectly found an over-broad intended purpose of the claimed invention by relying too heavily on extrinsic evidence. The Federal Circuit acknowledged that while “the patents themselves are the most important” evidence, “it is appropriate to consider extrinsic evidence, particularly when it does not contradict the patents themselves.” The Court went on to conclude that the intended purpose here was broader than the narrow purpose argued by Medtronic (relating to difficult occlusions)—“[t]he very title of the patents themselves, ‘Coaxial Guide Catheter for Interventional Cardiology Procedures,’ describes the purpose of the claimed inventions, and it is undisputed that the claim language does not impose any further purpose than this.”

Applying this purpose to Medtronic’s second challenge basis, the Federal Circuit found that the testing performed on the prototype was sufficient to show that the claimed invention worked for its intended purpose. The Court found that the testing relied on by the Board, while admittedly “more qualitative than quantitative,” was sufficient to enable the inventors to confirm that the prototype would work for its intended purpose.

Finally, Medtronic argued that the evidence of actual reduction to practice was insufficiently corroborated. The Federal Circuit agreed that inventor testimony may serve as evidence of reduction to practice but must be corroborated by independent evidence. However, the Court explained that corroborating evidence may be circumstantial and need not identify every individual aspect of reduction to practice. The evidence simply needs to be sufficient to support the credibility of the inventors’ story. Here, the Court found sufficient corroboration in the testimony offered by a former research and development technician and by the former Vice President of Regulatory and Clinical Affairs in support of the inventors’ testimony, along with documentary evidence such as reports and invoices showing purchases for prototypes consistent with the claimed invention.

Judge Dyk dissented based on the issue of corroboration. Judge Dyk was not convinced that actual reduction to practice was proven or that the inventors’ testimony was sufficiently corroborated. He found the non-inventor testimony insufficient in terms of corroboration, as it was directed to prototypes developed in early 2005 while the inventor testimony referenced prototypes developed in April and July 2005. He also criticized the evidentiary value of documents relating to the purchasing of parts: “This may corroborate assembly of prototypes but hardly corroborates testing, let alone successful testing by the critical date.”