EPO Enlarged Board of Appeal’s decision G1/23: repeated obtaining of the product constitutes a possible way of reproduction
The European Patent Office (EPO) Enlarged Board of Appeal’s decision in G1/23 was published in July 2025, shedding light on interpretation of G 1/92 and the enablement requirement for products put on the market as forming part of the state of the art within the meaning of Articles 54(2) and 56 EPC.
The referral
The referral originates from Technical Board of Appeal 3.3.03 in T 438/19. The Technical Board referred three questions to the Enlarged Board of Appeal concerning whether a product put on the market should be excluded from the state of the art where its composition or internal structure could not be analysed and reproduced without undue burden by the skilled person.
The referral originates from proceedings relating to European patent 2626911 in which granted claim 1 was directed to a material suitable as an encapsulating material for solar cell, which comprises an ethylene/alpha-olefin copolymer. A decision as to whether the subject-matter of granted claim 1 involved an inventive step ultimately depended on the question of whether the (commercially available) product ENGAGE® 8400 had been made available to the public before the effective date of the patent.
Up until now, the position at the EPO in deciding whether a product as such is available to the public has been led by G 1/92, where the Enlarged Board gave the opinion that:
“1. The chemical composition of a product is state of the art when the product as such is available to the public and can be analysed and reproduced by the skilled person, irrespective of whether or not particular reasons can be identified for analysing the composition.
2. The same principle applies mutatis mutandis to any other product”.
However, the Technical Board of Appeal in T 438/19 were of the view that:
“[O]pinion G 1/92 has given rise to diverging interpretations by the Boards of Appeal over the past 30 years, leading to legal uncertainties when it comes to assessing what constitutes state of the art within the meaning of Article 54(2) EPC in relation to a commercially available product. This results in the need to refer a number of questions to the Enlarged Board of Appeal, both to ensure uniform application of the law and because points of law of fundamental importance have arisen. A decision as to under which conditions for a product put on the market before the filing date, as is the case for ENGAGE® 8400, the product itself and partial information about its composition published prior to the filing date is state of the art within the meaning of Article 54(2) EPC is relevant to the present case, as the possibility to use such a product in the analysis of inventive step is decisive to determine the outcome of the case. In addition, the diverging interpretations made of G 1/92 are of considerable practical relevance in a large number of cases as illustrated by the various decisions mentioned above, and a mere theoretical importance is excluded”.
For these reasons, the Technical Board of Appeal decided to refer the following questions to the Enlarged Board of Appeal:
“1. Is a product put on the market before the date of filing of a European patent application to 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 without undue burden by the skilled person before that date?
2. If the answer to question 1 is no, is technical information about said product which was made available to the public before the filing date (e.g. by publication of technical brochure, non-patent or patent literature) state of the art within the meaning of Article 54(2) EPC, irrespective of whether the composition or internal structure of the product could be analysed and reproduced without undue burden by the skilled person before that date?
3. If the answer to question 1 is yes or the answer to question 2 is no, which criteria are to be applied in order to determine whether or not the composition or internal structure of the product could be analysed and reproduced without undue burden within the meaning of opinion G 1/92? In particular, is it required that the composition and internal structure of the product be fully analysable and identically reproducible?”
Key considerations
The Enlarged Board analysed the different interpretations of the “reproducibility requirement” set out in opinion G 1/92. It found that - beside manufacturing the product from starting materials that were different from the product itself - the repeated obtaining of the product from the market also constituted a possible way of reproduction for the skilled person. Accordingly, the “reproducibility requirement” must be understood in a broader sense, namely as the ability of the skilled person to obtain and possess the physical product. This requirement was inherently fulfilled by a product put on the market. Publicly available technical information on such a product also belonged to the state of the art, irrespective of whether the skilled person could reproduce the product and its composition or internal structure.
The Enlarged Board said:
“The chemical composition of a product is part of the state of the art when the product as such is available to the public and can be analysed by the skilled person, irrespective of whether or not particular reasons can be identified for analysing the composition” (paragraph 73 of the decision)
and:
“All analysable properties of the product put on the market became public” (paragraph 91 of the decision)
In other words, all properties of the product and its chemical composition or internal structure will belong to the state of the art to the extent they are analysable. There is no requirement for the product to be reproducible. All that matters is that the properties were able to be analysed.
The Enlarged Board held that it was not necessary to consider the “requirement of analysability” of a commercially available product separately from the “requirement of reproducibility” in order to answer the referred questions which concerned the joint condition “analysed AND reproduced”.
The order
The answers provided by the Enlarged Board thus were:
“I. A product put on the market before the date of filing of a European patent application 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.
II. Technical information about such a product which was made available to the public before the filing date forms part of the state of the art within the meaning of Article 54(2) EPC, irrespective of whether the skilled person could analyse and reproduce the product and its composition or internal structure before that date.”
Comments
G 1/23 thus does not provide an absolute on-sale bar - if a product is sold in public, the EPO will consider this a disclosure just like any other public disclosure and all “analysable” properties will be prior art. Even following G 1/23, non-analysable structural features of a product put on the market can remain hidden and do not form part of the prior art. It is however not clear at present whether there is an undue burden threshold for the analysability criterion.
As to the possible subsequent unavailability or modification of the product, the Enlarged Board stated that this might make it more difficult to establish and prove some property of the product (including its exact or partial composition). However, this problem of proof had no influence on the legal character of the product as belonging to the state of the art because the abstract teaching that had been derivable from it could not disappear retrospectively.
A non-public sale will not form part of the state of the art. Similarly, use of a product under controlled conditions, such as in a clinical trial, such that a skilled person cannot access and analyse the product may still not have a prior art effect in Europe.
