The Secret Prior Art Problem Rears Its Ugly Head
January 31, 2025 | Andrew Berks |Most people know that patents require absolute novelty, but how is that determined? It’s determined on the basis of “prior art,” that is, patents and other disclosures (journal articles, presentations, websites) that were made prior to the filing date of the patent. In some instances, these dates can be tricky and open to dispute.
The Federal Circuit upheld the invalidity of a patent owned by Lynk Labs, where the central issue was the date a published patent application is considered prior art in an Inter partes review (IPR) – the filing date of the patent or date of publication.
The Federal Circuit panel here agreed with PTAB that the filing date – not the publication date – was the controlling factor because the relevant prior art was within the scope of 35 USC §102(e). This case raises the issue of secret prior art, which I have previously discussed as a flaw in US patent jurisprudence. Unfortunately, this case upholds the secret prior art doctrine which is harmful to patentees.
The relevant dates are tabulated here:
Patent app/patent | Earliest Priority Date | Publication Date |
Martin (’970) | 2003-04-16 | 2004-10-21 |
’400 | 2004-02-25 |
Pre-AIA law applies because the ’400 patent was filed prior to March 16, 2013. It can be seen that Martin is a §102(e) reference against the ’400 patent – it was filed prior to the ’400 priority date but published after (§102(e): “the invention was described in — (1) an application for patent, published under section 122(b) [i.e., a patent publication], by another filed in the United States before the invention by the applicant for patent.”).In the IPR, Lynk argued that Martin was not valid prior art because it was published after the filing date of the ’400 patent, but this was argument was rejected by the PTAB which found the claims invalid as obvious over Martin and other references.
On appeal, Lynk renewed its argument that Martin was not prior art to the ’400 patent because, although Martin was filed before the ’400 patent’s priority date, it was published (and thus became publicly accessible) only thereafter.
Statutory interpretation
The opinion has an extensive discussion of statutory interpretation of §102(a), (b), and (e), and §311(b). Section 311(b) provides that an IPR petitioner may challenge a patent “only on a ground that could be raised under [35 U.S.C. §§] 102 or 103 and only on the basis of prior art consisting of patents or printed publications.” 35 U.S.C. §311(b) (emphasis added).
There is no dispute that Martin is a printed publication.
However, according to the opinion, Lynk only analyzed the prior art status of Martin under §102(a) and (b). The cases Lynk Labs cited stood for the proposition that, to be a prior art printed publication as to a given patent under one of these subsections, the reference at issue must have been publicly accessible before the date indicated in those sub-sections (here, for the ’400 patent, that relevant date is its priority date).
So Lynk argued that because Martin became publicly accessible only as of its Oct. 21, 2004, publication date and because the ’400 patent’s priority date is Feb. 25, 2004, Martin cannot be a prior art printed publication under §311(b) as to the ’400 patent.
The Federal Circuit panel explains this argument is deficient because Martin falls within the scope of §102(e). Under §102(e), a U.S.-filed patent application published under §122(b) serves as prior art to a claimed invention if the application was “filed … before the [claimed] invention.” §102(e)(1) (emphasis added).
In other words, under §102(e)(1), even if a patent application was published after a claimed invention, it may serve as prior art to the invention if the application was filed before the invention. The effective date under §102(e) as prior art against another patent application is the date the patent application was filed, not the publication date.
The panel concludes that since §311(b) permits IPR challenges based upon “prior art … printed publications,” it includes within its literal scope challenges based on a published patent application.
And, by virtue of §102(e)(1), a published patent application—a specific type of “printed publication”—is deemed prior art as of its filing date — not its publication date. The panel asserts that this was the intent of Congress in enacting §102(e). Therefore, Martin was properly deemed prior art to the ’400 patent in this IPR and the obviousness findings by the PTAB were upheld.
The Secret Prior Art Problem
This case does not use the words “secret prior art” – but that is exactly the problem raised here. As a matter of policy, patents require absolute novelty. So a novelty rejection based on §102(e) (or AIA §102(a)(2)) is not objectionable. If the inventor was not the first to make an invention, that inventor is not entitled to a patent.
Under §102(e), a patent or printed publication becomes prior art as of its filing date – not its public disclosure date, but because the issue is absolute novelty, the inventor cannot be said to have been the first to make the invention. But an obviousness argument is a different analysis.
The obviousness statute (pre-AIA §103(a)) provides:
(a) A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. (emphasis added).
The AIA version of §103 is substantially similar, except it refers to “the effective filing date of the claimed invention,” instead of “at the time the invention was made.”
Thus, under a plain reading of §103, a reference can be held as prior art only if it was known at the time the invention was made (pre-AIA) or on the effective filing date of the claimed invention (AIA) – that is, if the reference was published or otherwise publicly accessible prior to the date the invention was made (pre-AIA) or prior to the effective filing date. Note, too, that this case (Lynk v. Samsung) makes a big point that public accessibility is a “touchstone” of a printed publication (slip op. at 6 and 16).
However, Lynk v. Samsung and other cases hold that secret prior art, that is, cases under §102(e) that were filed before an invention was made (or a filing date in the AIA), but published after, can be treated as prior art under §103.
Although Lynk v Samsung refers mainly to §311(b), Samsung’s IPR petition argued obviousness, and the opinion discusses Lynk claim construction arguments, which if successful would have obviated the combination of Martin and several other references, i.e., under an obviousness analysis.
Tension between Sections 102 and 103
Thus, there is an unresolved tension between pre-AIA §102(e) (and AIA §102(a)(2)) and §103. Does a finding of obviousness require that prior art (regardless of a patent or other publication) be publicly accessible at this time of invention/filing?
If one reads §103 and stops the analysis at “disclosed or described as set forth in section 102…” then secret prior art within the scope of pre-AIA §102(e) and AIA §102(a)(2) is acceptable in an obviousness analysis. But if one reads §103 in full, which also includes the words “the effective filing date of the claimed invention,” or “at the time the invention was made” – then these words suggest that only the subset of §102 references publicly available at the time the invention was made or filed should be used.
It is also significant that that the Federal Circuit, in Lynk v. Samsung, makes a point that congress intended to treat §102(e) as having a different prior art effect than in §102(a) or (b) with a discussion of the “temporal effect” of prior art (slip op. at 16), meaning the date a reference is effective prior art. This logic also suggests that the language in §103 should control the prior art effect for obviousness references, so that only references publicly accessible at the time of invention or filing are appropriate for an obviousness argument.
The Lynk opinion is primarily directed to the IPR statute (§311(b)), but the arguments pertain to obviousness (§103), since obviousness was the issue in the Samsung IPR petition.
The Lynk opinion goes to great length to apply §102(e) to IPR’s without touching on the applicability to the obviousness statute (§103), and without addressing the plain language of §103 that prior art is assessed at the time the invention was made (pre-AIA) or the time of filing (AIA), not some secret date, prior to the date of the invention or filing, based on an arbitrary interpretation of the applicable statutes.
An additional comment is that under the European Patent Convention (EPC) and Canadian Patent Law, for an obviousness argument, a reference is only available as of its publication date, not its filing date.
For the EPC, see Art. 56, covering Inventive Step (this is the same as obviousness in US practice) which specifically excludes a reference within the scope of Art. 56(3), which is the EPC equivalent to 35 USC §102(a)(2) (pre-AIA §102(e)). In Canada, the Patents Act §28.3 only permits references for obviousness when “the information became available to the public in Canada or elsewhere.”
Conclusion
The Lynk v. Samsung decision reinforces the secret prior art doctrine. The United States is an outlier among other major patent authorities in holding inventors accountable for secret prior art, to the detriment of patentees.
Reprinted with permission from the January 31, 2025, issue of the New York Law Journal©, ALM Media Properties, LLC. Further duplication without permission is prohibited. All rights reserved.