3.2.4 Public prior use
In many cases the ability to recognise a technical teaching such as the internal structure or composition of a product in prior use presupposes analysis of the product embodying this technical teaching. Whether it is technically feasible to analyse a product that is available on the open market is an issue that the boards have considered on a number of occasions.
In T 952/92 (OJ 1995, 755) the board stated that information as to the composition or internal structure of a prior sold product is made available to the public and becomes part of the state of the art if direct and unambiguous access to such information is possible by means of known analytical techniques which were available for use by a skilled person before the relevant filing date (see also T 2/09). The board also stated that the likelihood or otherwise of a skilled person analysing such a prior sold product, and the degree of burden (i.e. the amount of work and time involved in carrying out such an analysis), is in principle irrelevant to the determination of what constitutes the state of the art. The novelty of a claimed invention is destroyed by the prior disclosure (by any means) of an embodiment which falls within the claim. The possibility of a complete analysis of a prior sold product is not necessary. The novelty of a claim is destroyed if an analysis of a prior sold product is such as to inform the skilled person of an embodiment of the product which falls within the claim.
In G 1/92 (OJ 1993, 277) the Enlarged Board held that the chemical composition of a product forms part of the 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. The same principle applies mutatis mutandis to any other product. It also stated that "[a]n essential purpose of any technical teaching is to enable the person skilled in the art to manufacture or use a given product by applying such teaching. Where such teaching results from a product put on the market, the person skilled in the art will have to rely on his general technical knowledge to gather all information enabling him to prepare the said product. Where it is possible for the skilled person to discover the composition or the internal structure of the product and to reproduce it without undue burden, then both the product and its composition or internal structure become state of the art". However, the Enlarged Board added that "a commercially available product per se does not implicitly disclose anything beyond its composition or internal structure. Extrinsic characteristics, which are only revealed when the product is exposed to interaction with specifically chosen outside conditions, e.g., reactants or the like, in order to provide a particular effect or result or to discover potential results or capabilities, therefore point beyond the product per se as they are dependent on deliberate choices being made. Typical examples are the application as a pharmaceutical product of a known substance or composition (see Article 54(5) EPC) and the use of a known compound for a particular purpose, based on a new technical effect (see G 2/88, OJ 1990, 93). Thus, such characteristics cannot be considered as already having been made available to the public". See below on T 472/92, T 834/15, T 1409/16 and T 1666/16 which (among other things) discuss the issue of extrinsic characteristics.
In T 438/19, the board identified diverging approaches to applying the criteria of G 1/92 as to analysability and reproducibility of a product that has been put on the market, and when and to what extent it should be considered part of the state of the art. As a result, the board referred the following questions to the Enlarged Board:
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 Art. 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 Art. 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?
The Enlarged Board issued its decision G 1/23 on 2nd July 2025 date: 2025-07-02.
(i) Structure or composition made available to the public
In T 390/88 a photographic film had been made available to the public by announcement at a press conference three weeks before the priority date. The board held that this relatively short time interval was sufficient to enable interested parties to become fully aware of the film's composition.
In T 969/90 and T 953/90 the board ruled that the internal structure of a product in prior use had been made available to the public because a skilled person relying on the normal means of investigation available to them would have been able to analyse the product.
In T 301/94 the board decided that the skilled person would have been able to reproduce the green glass without undue burden and that this was sufficient to meet the requirement of reproducibility set out in G 1/92. A skilled person must be able to prepare the product without undue burden on the basis of his general technical knowledge and knowing the composition or internal structure of the product, whatever the scale of production (laboratory, pilot or industrial scale). The board held that when a commercially available product could be analysed by the analytical methods known on the priority date and could also be reproduced, its chemical composition formed part of the state of the art even if a skilled person could not have recognised a priori (i.e. before performing an analysis), on the basis of the common general knowledge on the priority date that at least one component was present in the product, or was present in an "unusual small" amount (referring to T 952/92, OJ 1995, 755; T 406/86 OJ 1989, 302; T 390/88; G 1/92; see also T 370/02).
In T 947/99 the alleged public prior use concerned a visit to an ice-cream factory. Although it had not been established that a feature of the manufacturing process had been explicitly explained to the visitors, the board decided that information about the procedure had been publicly disclosed. The board observed that, in accordance with the principles set out in G 1/92, it was the fact that direct, unlimited and unambiguous access to any particular information regarding the manufacturing processes known per se was possible which made these processes available to the public within the meaning of Art. 54(2) EPC 1973, whether or not there was any reason to look or ask for such information.
In T 2068/15 (chemical composition – analysability), the board considered in the case at issue that the skilled person analysing the film with the techniques known at that time (electron microscopy) would not have overlooked the first top layer. And the board stated also that it was common practice at the priority date of the patent to apply more than one analytical method in order to obtain information about the composition of a material.
In T 1409/16 the board decided that commercial composition only accessible by subjecting said prior art composition to a kind of reverse engineering (by fractionation) based on hindsight revealed "extrinsic characteristic" within the meaning of G 1/92 (see also similar case T 834/15).
In T 1452/16 (alleged prior use of Amano lactase) the board stated that in order to assess whether a prior-art product falls within the terms of the claim, one obviously has to assess the claimed parameters, even if these have never been used before. Furthermore, the board explained in detail why the present cases differed from T 946/04, T 1457/09, T 2048/12 and T 2068/15. Contrary to the patent proprietor's arguments, the board noted firstly that T 952/92 did not stipulate that structural assays had to be used, and second that the skilled person did not have to test for all possible impurities. As to reproducibility, T 952/92 also clarified that no complete reproducibility was needed. The board came to the conclusion that the evidence on file convincingly demonstrated that a lactase preparation fulfilling the parameters (given ratio) recited in claim 1 of the main request was publicly available, that an enzyme with the characteristics as claimed was commercially available in the prior art and that its use in a process as claimed had also been made available to a member of the public, and hence was state of the art. See also T 1540/21.
(ii) Structure or composition not made available to the public
In T 461/88 (OJ 1993, 295) the board ruled that a control program stored on a microchip had not been made available to the public if the analysis of the program would require an expenditure of effort on a scale which could only be reckoned in man-years and if, for economic reasons, it was highly improbable that the sole purchaser of the machine controlled by the program had carried out such an analysis (see obiter dictum in T 969/90, see also T 212/99).
In T 472/92 (OJ 1998, 161) the board referred to G 1/92 and concluded that the printability characteristic of the material was not a property that became available to the public by their mere delivery, since this was clearly an extrinsic characteristic requiring interaction with specifically chosen outside conditions. Thus, such characteristic could not be considered as already having been made available to the public (see also T 267/92).
The board in T 1217/01 found that, since the perming product allegedly in prior use was a fast-moving consumer good, it could be presumed that it had gone on sale, and so been publicly available, soon after payment of the invoice the appellant (opponent) had adduced as supporting evidence. For the board, the case turned on the composition of the oxidising agent (fixer) in the invoiced product. But, as no product or even packaging dating from the time was available, its exact composition could be deduced only by "reverse reasoning", working back from the process of its elaboration and production. The board ultimately found that the evidence was not conclusive enough; owing especially to changes in the product names and numbers, it had not been shown that the sold product had also been made of the claimed composition.
In T 2048/12 the board stated that opinion G 1/92 did not imply that in each and every case the commercial availability of a chemical product as such necessarily amounted to a disclosure of (also) all the impurities contained therein merely because it was possible to identify and quantify these impurities by analytical means. Conclusion 1 of G 1/92 was to be read by attributing a technically reasonable meaning to the technical expression "chemical composition". In the present case there was no direct or indirect pointer to the possible technical relevance of further impurities (besides water) in the commercial product.
T 1833/14 dealt with the condition of reproducibility laid down in G 1/92. It could not be concluded that the skilled person was able to reproduce the product Rigidex®P450xHP60 without undue burden. In order to be part of the prior art pursuant to Art. 54(2) EPC, a public prior use must amount to an enabling disclosure (T 977/93, OJ 2001, 84; T 370/02, T 2045/09, T 23/11 and T 301/94). It is generally known in the field of polymers that the nature of the catalyst system, the type of reacting system and the process conditions significantly affect the properties of the produced polymer. In the polymer field, in which products and compositions are often defined by means of parameters, the requirements of sufficiency of disclosure is analysed with particular care and the same criteria must apply to the reproducibility without undue burden of a product on the market. In order for the product to be state of the art, the question was whether or not the skilled person would have been in a position to prepare the product as such, i.e. a sample identical to Rigidex®P450xHP60 in all its properties (not only those specified in claim 1). This was however not shown by the appellant (opponent). To the contrary, the appellant stated that "what may be more difficult (if the catalyst used for the original product is not known) is obtaining the same mechanical properties as the Rigidex product". T 1833/14 cited by T 842/14 and T 2916/19 in connection with Art. 83 EPC.
In T 1666/16 (powders – angle of repose), the board could not conclude that the skilled person was able to determine the internal structure of the sold products and to reproduce them without undue burden at the date of their sale; the internal structure of these products did not form part of the prior art. The issue of extrinsic characteristics in view of G 1/92 was also at stake.
- G 0001/23
In G 0001/23 the Enlarged Board answered the referred questions as follows:
"1. 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.
2. 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.
3. In view of the answers to Questions 1 and 2 an answer is not required."
The Enlarged Board decided that in interpreting the referred questions, it was not needed to treat analysability independently from reproducibility. The questions turned on the requirement of reproducibility and whether this was indeed a valid condition of an available product for forming part of the state of the art. The Enlarged Board highlighted that the prior art status of non-reproducible man-made products put on the market and non-reproducible naturally occurring materials can be assessed similarly. In addition, the term "reproduce" could cover two possibilities: obtaining again a product put on the market in its readily available form, as well as for the skilled person to manufacture the product themselves. In the context of the referral, the EBA understood the term "reproduce" in the latter, more limited sense. In any event, "reproducibility" was to be understood as being only on the basis of the common general knowledge the skilled person has before the filing date.
The EBA concluded that both interpretations of G 1/92 proposed by the referring board and existing case law lead to absurd results. The first interpretation postulated that non-reproducible but otherwise existing and commercially available products do not belong to the state of the art. The EBA saw this interpretation as establishing a legal fiction overriding facts and which was not explicitly stated in the law. The second interpretation, according to which only the composition of a non-reproducible product is excluded from the prior art, was also seen to lead to absurd results. All starting materials used by the skilled person must be selected on the basis of their desired properties, which in turn are determined by the composition of the material. Also the very first raw material in the production chain inevitably had to come from a natural source. Its composition must be known and consciously exploited by the skilled person, even where they would not be able to reproduce the composition by a different route. The non-reproducible property, the composition, could not be ignored or disregarded, or else there would be no material left for the skilled person to work with.
The EBA therefore provided the correct interpretation of G 1/92 and held that the expected reproducibility of the product must be understood in a broader sense, namely as the ability of the skilled person to obtain and possess the physical product. This meant that the requirement would be inherently fulfilled by a product put on the market. The proper reading of the answer of G 1/92 was set out as follows: "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."
In turn, this meant that all analysable properties of a product put on the market become public alone by the possibility that they can been analysed, because the product was physically accessible. If the composition can be analysed, this becomes part of the state of the art as well, also if the skilled person is not in the position to reproduce it on their own.
The EBA also explained that prior art that is not considered relevant does not mean that the prior art does not exist. Something that belongs to the existing state of the art need not be relevant for any invention and for all provisions of the EPC where the state of the art is to be taken into account. That a non-reproducible product belongs to the state of the art does not necessarily mean that the product or its features must be taken into account equally when assessing novelty or inventive step.