A product on the market is prior art at the EPO even if no one could analyse or reproduce it

2025-07-02EPO

Decision of the Enlarged Board of Appeal G 1/23 (2 July 2025), Solar cell sealing material, and solar cell module / Mitsui Chemicals, on referral from Technical Board of Appeal decision T 438/19

The referral came from Technical Board 3.3.03 in an opposition appeal against Mitsui Chemicals' European patent No. 2 626 911, where the closest prior art was a commercial polymer, ENGAGE 8400. Opinion G 1/92 had been read to make a marketed product state of the art only if the skilled person could analyse and reproduce it, and the referring board asked whether a product that could not be analysed and reproduced without undue burden is excluded, and whether published information about it still counts. The Enlarged Board answered that a product put on the market before the filing date "cannot be excluded from the state of the art within the meaning of Article 54(2) EPC for the sole reason that its composition or internal structure could not be analysed and reproduced by the skilled person before that date," and that technical information about such a product made public before filing is state of the art "irrespective of whether the skilled person could analyse and reproduce the product." It held that the answer in G 1/92 "cannot be maintained in its entirety," that "all analysable properties of the product put on the market will belong to the state of the art," that a non-reproducible product "still cannot be ignored for novelty," and that its features may, but need not, enter the inventive step analysis.

What it changesA model that ships is prior art at the EPO for everything the public can observe or analyse about it, even though nobody outside the company can rebuild its weights or its training run. That reaches the behaviour of a deployed model, its outputs and interface, its published model card and technical report, and, for a model distributed on a device, whatever architecture and parameters a skilled person can extract from the file. Europe has no general grace period, so a company that launches first and files afterwards on what its product does will meet its own product as novelty-destroying or obviousness art. File before any public beta, application programming interface access or on-device release, and treat benchmark disclosures and model documentation as publications on the filing calendar. For freedom-to-operate work, a competitor's earlier product is now usable art even where its internals were secret.

More on Prior art, public disclosure and obviousness

← All recent developments · Search all developments

Burbage Law is the practice of Jon Burbage, a registered patent attorney. 342 United States patents have issued from applications he wrote; the full list is on the Patents page. More about Jon Burbage.

This is general information about a published decision, agency guidance or piece of legislation. It is not legal advice and does not create an attorney-client relationship. Items concerning offices outside the United States are reported for information only and are not counsel on the law of those countries.