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 of Appeal 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 "An 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."

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).

In T 390/88 the board rejected the argument that a film had not been made available to the public because its existence had only been announced at a press conference three weeks before the priority date, and hence it would have been impossible in that short time for a person skilled in the art to determine the film's composition.

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 969/90 and T 953/90 the board had 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 him would have been able to analyse the product.

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.

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.

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 ruling in T 969/90, see also T 212/99).

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 in connection with Art. 83 EPC.

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.