Under Art. 64(2) EPC (1973 and 2000) the protection conferred by a process patent extends to the products obtained directly by the process, even if they are not patentable per se. Certain applicants tried to acquire protection for known products by using process claims to define them, arguing that it follows from Art. 64(2) EPC 1973, that a product is rendered novel by the fact that it is produced by means of a new process.

The boards of appeal did not accept this line of argument and made a distinction between claims to a new and inventive product defined by its method of manufacture and claims to a new and inventive process, the protective effects of which also extended to the direct products of this process.

The first decision in this regard was T 150/82 (OJ 1984, 309). The board stated that claims for products defined in terms of processes for their preparation (known as "product-by-process" claims) were admissible only if the products themselves fulfilled the requirements for patentability and there was no other information available in the application which could have enabled the applicant to define the product satisfactorily by reference to its composition, structure or some other testable parameter (established case law, see e.g. G 2/12, OJ 2016, A28 and G 2/13, OJ 2016, A29; T 956/04; T 768/08; T 150/12).

With regard to product-by-process claims, the requirement of clarity means that the skilled person should be able to determine, either from the claim alone or, by construction of the claim in the light of the description, or by construction in the light of the skilled person's common general knowledge, which identifiable and unambiguous technical features are imparted to the product by the process by which it is defined (T 967/10, T 1988/12). In T 1988/12 the board rejected the idea that the claim was necessarily clear if a skilled person (i.e. a plant breeder) could determine whether or not a candidate plant fell within its terms. The suggestion that the skilled person had to rely on an analysis of a potentially infringing product to know what the subject-matter for which protection was sought actually was, ran counter to the purpose of Art. 84 EPC.