An inventor’s testimony of his/her invention date requires independent corroboration. But can that evidence come from a machine rather than a person? In Google LLC v. Valtrus Innovations Ltd., Appeal No. 2024-1945 (Fed. Cir. Oct. 19, 2026), the Federal Circuit concluded that metadata automatically generated by Microsoft Word can independently corroborate an inventor’s testimony. The court also concluded that eleven business days spent returning a signed application oath to counsel and filing the application did not undermine otherwise reasonably continuous diligence.
Google’s IPR petition challenged a Valtrus Innovations patent on merging search results from multiple search engines. Every ground relied on a reference filed about five weeks before the patent’s August 27, 2001, filing date. Valtrus, Slip Op. at 2–3. That filing date subjects the patent to the pre-AIA first-to-invent law. Under that law, Valtrus could disqualify the reference by proving the inventors conceived or actually reduced to practice the claimed invention (or at least the reference’s applied disclosure) before its effective date. See pre-AIA 35 U.S.C. § 102(e). Valtrus submitted an inventor’s declaration stating that he and his co-inventors conceived the invention before the reference’s effective date and diligently worked to file the application, a practice called “swearing behind” the reference. Valtrus also relied on original invention disclosure documents and their native metadata. Based on all this evidence, the Board concluded that Valtrus had successfully sworn behind the reference and, thus, rejected the challenged grounds, upholding the patent’s claims. Id. at 3–4.
Google argued the inventor’s testimony wasn’t sufficiently corroborated because the documents and their metadata were the inventor’s “own statements and documents.” But the court explained that Microsoft Word, not the inventor, generated the metadata, making it independent of him even if he authored the documents. Id. at 7 (citing Global Health Sols. LLC v. Selner, 148 F.4th 1363, 1374 (Fed. Cir. 2025)). That “disclosure metadata,” said the court, is unlike “unwitnessed lab notebooks” and “drawings” that “alone cannot corroborate an inventor’s testimony of conception.” Id. at 7–8 (citing Apator Miitors ApS v. Kamstrup A/S, 887 F.3d 1293, 1297 (Fed. Cir. 2018)). The metadata was important to Valtrus’s successful defense. Contrast Kolcraft Enterprises, Inc. v. Graco Children’s Products, Inc., 927 F.3d 1320 (Fed. Cir. 2019), which we discussed here, where the patent owner lost because it offered inventor testimony about metadata rather than the metadata itself. The Valtrus court assumed, without deciding, the metadata was authentic. Valtrus, Slip Op. at 7.
The diligence dispute centered on the eleven business days between the last co-inventor’s August 8 signature on the inventorship oath and the application’s August 27 filing. Under Perfect Surgical Techniques, Inc. v. Olympus America, Inc., 841 F.3d 1004, 1009 (Fed. Cir. 2016), which we discussed here, Valtrus needed only show “reasonably continuous” diligence, not daily activity. The last co-inventors’ signed oath apparently had to travel by mail from his location in Canada to Valtrus’s law firm in California, and Valtrus’s expert testified that firms “need several weeks or more” to draft and finalize an application. Valtrus, Slip Op. at 9–10 (citing D’Amico v. Koike, 347 F.2d 867, 871 (CCPA 1965)). These “nonspeculative facts,” the court concluded, constitute substantial evidence supporting the Board’s finding of such diligence. Id. at 10.
To support its diligence challenge, Google relied on In re Mulder, 716 F.2d 1542 (Fed. Cir. 1983), where just two days without diligence apparently cost the applicant his conception date. Valtrus, Slip Op. at 10. But the court said that reliance “is misplaced,” noting Judge Rich’s caution in Mulder that “focus[]ing on the shortness of the gap is misleading.” Id. There, a draft application sat for nearly three months without relevant activity, encompassing the two-day gap between the reference’s effective date and the applicant’s filing date. Mulder, 716 F.2d at 1545. Valtrus, by contrast, used timestamps to prove the inventors’ and law firm’s collaborative activities during the relevant diligence period. Valtrus, Slip Op. at 10. That analysis seems consistent with ATI Technologies ULC v. Iancu, 920 F.3d 1362, 1369 (Fed. Cir. 2019), which we discussed here, where the court reversed the Board for demanding “continuous reasonable diligence” and faulted the patent owner for not ruling out unexplained lapses.
The evidentiary lessons of Valtrus extend beyond the pre-AIA validity defense in which they arose. Patent owners should preserve native files, introduce relevant metadata into inter partes proceedings, and try to document daily diligence, including mailing, signatures, and law-firm activity. Although the Director’s controversial “settled expectations” factor makes inter partes reviews challenging pre-AIA patents seem unlikely, validity challenges relying solely on disqualifiable prior art remains perilous. Challengers should focus less on short, likely explainable diligence gaps and more on metadata’s authenticity and chain of custody. Valtrus seems to have left those issues open while confirming that machine-generated evidence can supply legally required independent corroboration. Whether that corroboration is sufficient remains a question of fact, so the decision confirms a fact finder may credit such evidence, not that it must.