Under Art. 53(c) EPC methods for treatment of the human or animal body by surgery or therapy and diagnostic methods practised on the human or animal body ("medical methods") are excluded from patentability; this provision shall not apply to products, in particular substances or compositions, for use in any of these methods (see former Art. 52(4) EPC 1973).
Art. 54(4) EPC (former Art. 54(5) EPC 1973) provides that the general rules of law relating to novelty do not exclude the patentability of any substance or composition, comprised in the state of the art, for use in a method referred to in Art. 53(c) EPC (former Art. 52(4) EPC 1973), provided that its use for any method referred to in that paragraph is not comprised in the state of the art. Thus in addition to the general concept of novelty, this article introduces, in respect of substances and compounds used in surgical and therapeutic treatment and in diagnostic processes carried out on humans and animals, a special concept of novelty unknown in other technical fields (T 128/82, OJ 1984, 164). In the EPC 2000 some of these provisions have been amended but their substance remains unchanged.
Accordingly, under Art. 54(4) EPC (former Art. 54(5) EPC 1973), known substances or compositions are deemed to be new, provided they are used for the first time in such a medical method. According to the case law of the boards of appeal, the first to show a use of a substance or composition in a medical method should receive broad protection covering any use in a medical method, even if only one specific use is disclosed in the application (see T 128/82, OJ 1984, 164; T 36/83 OJ 1986, 295).
For the first medical use of a known substance, Art. 54(4) EPC (former Art. 54(5) EPC 1973) provides a particular form of claim (purpose-related product claim). In G 5/83 (OJ 1985, 64) the Enlarged Board observed that the inventor of a "first medical indication" could obtain purpose-limited product protection for a known substance or composition, without having to restrict himself to the substance or composition when in a form technically adapted to a specified therapeutic purpose. The appropriate protection for him was, therefore, in its broadest form, a purpose-limited product claim.