Key Points

  • The Federal Circuit affirmed the PTAB's final written decision that Google failed to prove claims 1-23 of Valtrus's U.S. Patent No. 6,728,704 unpatentable.
  • The court held that Microsoft Word metadata, which the inventor did not author, can independently corroborate an inventor's conception testimony and the inventor's Word files.
  • The court upheld the board's finding that the Bushee reference is not prior art under pre-AIA 35 U.S.C. ยง 102(e) because Valtrus antedated it.
  • Substantial evidence supported reasonably continuous diligence over the roughly 11 business days between the last inventor signature on August 8, 2001, and filing on August 27, 2001.
  • The court distinguished In re Mulder, where the record showed no activity in the United States during a nearly three-month period after the draft application was ready.

A federal appeals court ruled Monday that the metadata Microsoft Word automatically attaches to a file can independently corroborate an inventor's account of when an invention was conceived, rejecting Google LLC's bid to cancel a search-engine patent owned by Valtrus Innovations Ltd.

The U.S. Court of Appeals for the Federal Circuit affirmed a decision of the Patent Trial and Appeal Board, which had concluded that Google failed to show that any of claims 1 through 23 of Valtrus's patent are unpatentable. Judge Cunningham wrote the opinion for a panel that also included Judge Hughes and U.S. District Judge Allison D. Burroughs of the District of Massachusetts, sitting by designation.

Patent owners who try to prove that their inventors came up with an idea before a competing reference was filed must offer evidence beyond the inventor's word. Assuming without deciding the metadata's authenticity, the panel held that Word's machine-generated author and timestamp data can satisfy that requirement, even when the data is stored in the inventor's own files. It also held that about 11 business days spent collecting a mailed signature and filing the application did not break the inventors' diligence.

Valtrus owns U.S. Patent No. 6,728,704, which claims methods for merging lists of search results from multiple search engines. Google challenged the patent through inter partes review. Google argued that the claims would have been obvious over a patent known as Bushee, combined with other references.

Bushee was filed on July 24, 2001, about five weeks before the application for Valtrus's patent was filed on August 27, 2001. Because the Valtrus application predates March 16, 2013, the pre-AIA, first-to-invent version of the patent statute applies. Under that version, a patent owner can "swear behind," or "antedate," an earlier-filed reference by showing that its inventors conceived of the invention first and then pursued it with "reasonably continuous diligence" until the application was filed.

The board found that Valtrus made that showing. It relied on a declaration from co-inventor Dr. Tsaparas, files containing the original invention disclosures and the files' original metadata, and analysis from Valtrus's expert, Dr. Cole. The parties marked the claimed conception date confidential, and the Federal Circuit said it did not need to identify that date to resolve the appeal.

On appeal, Google argued that the board relied on "legally insufficient" evidence. Google contended that the disclosure files and their metadata could not independently corroborate the inventor "because they are both entirely under Dr. Tsaparas's control." The court has said the corroboration rule reflects "a concern that inventors testifying in patent infringement cases would be tempted to remember facts favorable to their case by the lure of protecting their patent or defeating another's patent."

The panel rejected Google's argument. "Assuming without deciding the metadata's authenticity, the disclosure metadata generated by Microsoft Word was not authored by Dr. Tsaparas," Judge Cunningham wrote. The opinion relied on Global Health Solutions LLC v. Selner, a 2025 Federal Circuit decision, and held that "Microsoft Word metadata can provide independent corroboration of inventor statements and documents contained in Word files."

The court distinguished the metadata from the "unwitnessed laboratory notebooks" and "unwitnessed emails and drawings" that its earlier cases found insufficient on their own. The authorship and timestamp information in the metadata was consistent with the conception date Dr. Tsaparas gave in his declaration, the panel said. The opinion also noted that Google's counsel acknowledged at oral argument "that a human is not a required element for corroboration."

Google's second argument concerned the gap between August 8 and August 27, 2001. Google conceded that the inventors were signing the application through August 8 and disputed only the remaining period, which its counsel described at argument as about "11 business days."

The panel found substantial evidence, the deferential standard under which a finding stands if a reasonable mind could accept the evidence as adequate, to support the board's diligence finding. Dr. Tsaparas was in Ontario, Canada, at the time, and his August 8 signature, the last of the four inventors' signatures, had to travel by mail to the law firm's California offices. Dr. Cole gave his opinion that the applicant was diligent because it "take[s] law firms on the order of several weeks or more" to draft and finalize an application.

The court also quoted a 1965 decision of the Court of Customs and Patent Appeals, which said that "the law cannot presume that such people can immediately begin and expeditiously perform their duties as soon as work appears on their desks." "These non-speculative facts amount to substantial evidence support of the Board's finding," the panel wrote.

The court rejected Google's comparison to In re Mulder, a 1983 Federal Circuit decision in which an applicant lost his conception date over a two-day period without diligent activity. In Mulder, the court had said that "focus[]ing on the shortness of the gap [wa]s misleading." A draft application in that case had been prepared for nearly three months, and "the record show[ed] no activity of any kind in this country." Valtrus, by contrast, used timestamp evidence to account for the entire required period, including the disputed weeks, the panel wrote.

Nathan R. Speed of Wolf, Greenfield & Sacks, P.C. argued for Google. Philip J. Warrick of Irell & Manella LLP argued for Valtrus.

The panel said it had considered Google's remaining arguments and found them unpersuasive. The affirmance leaves in place the board's final written decision in IPR2022-01545, which upheld all 23 challenged claims of the '704 patent.