A substance or composition for which a first medical use is already known may nevertheless be patentable under Art. 54(5) EPC for a second or further use in a method under Art. 53(c) EPC if that use is novel and inventive. According to G 5/83 (OJ 1985, 64), a further medical use claim is a claim directed to the use of a substance or composition for the manufacture of a medicament for a specified therapeutic application. Such a claim is novel if the therapeutic application, i.e. the therapeutic effect obtained by the claimed use, is novel. The Enlarged Board explained the legal and historical background to the patentability of further medical uses in G 2/08 date: 2010-02-19 (OJ 2010, 456).

Under the EPC 1973 a patent for a further medical application could, pursuant to a line of case law first set out in decision G 5/83 (OJ 1985, 64), be granted for a claim directed to the use of a substance or composition for the manufacture of a medicament for a specified therapeutic application ("Swiss-type claim"). The novelty of the subject-matter of such a claim could be derived not only from the novelty of the substance or of the method of manufacture, but also from the new therapeutic application (G 5/83). This "special approach to the derivation of novelty" constituted a narrow exception to the general novelty requirement and was not to be applied in other fields of technology.

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 ("first use in a medical method"). In the early 1980s, the Enlarged Board of Appeal was asked to decide whether any further medical use could receive patent protection under the EPC in spite of the wording of Art. 54(5) EPC 1973 (now Art. 54(4) EPC) which seemed to limit patentability to the first medical use. The Enlarged Board extended the notional novelty provided for in former Art. 54(5) EPC 1973 to apply to each further medical use in the so-called "Swiss type claim", i.e. to a claim "directed to the use of a substance or composition for the manufacture of a medicament for a specified new and inventive therapeutic application" (G 5/83, OJ 1985, 64; Legal Advice from the Swiss Federal Intellectual Property Office, OJ 1984, 581).

During the course of the revision of the EPC 2000, former Art. 54(5) EPC 1973 ("first use in a medical method") was renumbered to become Art. 54(4) EPC and a new Art. 54(5) EPC was introduced to provide protection for second medical uses. The new Art. 54(5) EPC eliminates any legal uncertainty on the patentability of further medical uses. It unambiguously permits purpose-related product protection for each further new medical use of a substance or composition already known as a medicine.

Claims to a second medical use would be drafted as product claims relating to a specific second or further medical use (see T 1599/06).

In T 1314/05, the board stated that decision G 5/83 made it quite clear that its special approach to the derivation of novelty was applicable only to inventions or claims relating to the use of substances or compositions in a method of treatment referred to in Art. 52(4) EPC 1973, where that method did not yet form part of the state of the art. The board decided that G 5/83 did not imply that the special approach to novelty assessment which was associated with the Swiss-type claim for substances or compositions could be applied to the use of a device to produce an appliance intended for medical purposes. Extension of that special approach to the production of such appliances ran counter to the general legal principle that exceptions are to be construed narrowly. This was confirmed by the fact that the EPC 2000 legislator in Art. 54(5) EPC expressly restricted the exception concerning the second medical use to substances or compositions.

The board in T 1099/09 found that it followed clearly and directly from the EPC that Art. 54(4) and (5) EPC applied only to products which were substances or compositions and that no other products were patentable under them. The therapeutic effect of a medicinal product usually resulted from at least one substance or composition used in it and generally known as its active ingredient.

In T 1758/07 the board stated that G 5/83 only applies to second (and further) medical indications. It followed from this that the legal fiction behind G 5/83, namely that the therapeutic treatment according to Art. 52(4) EPC 1973 was a limiting feature, was applicable only if a therapeutic treatment was indeed a second (or further) medical indication. If, however, the claimed subject-matter related to the first medical indication, G 5/83 provided no legal basis for additionally claiming the same subject-matter as a second medical indication.

In G 2/08 date: 2010-02-19 (OJ 2010, 456), the Enlarged Board of Appeal considered the consequences of the revised EPC for claims in the Swiss-type format. It decided that, where the subject-matter of a claim is rendered novel only by a new therapeutic use of a medicament, such claim may no longer have the format of a so-called Swiss-type claim as instituted by decision G 5/83 (OJ 1985, 64). As Art. 54(5) EPC now permits purpose-related product protection for any further specific use of a known medicament in a method of therapy, the loophole existing in the provisions of the EPC 1973 is now closed – when the reason for the law ceases, the law itself ceases. In view of the fact that patents had been granted for claims of this (Swiss) type and many applications seeking such patent protection were still pending, the Enlarged Board considered that a transitional arrangement was necessary to ensure legal certainty and to protect the legitimate expectations of applicants. It therefore set a time limit of three months from publication of its decision in the Official Journal of the EPO for future applications to comply with the new situation. In this respect the relevant date for future applications was ordered to be their date of filing or, if priority had been claimed, their priority date.

G 2/08 date: 2010-02-19 is discussed in further detail in this chapter I.C.7.2.4 e) "New dosage regimen".

For the "Formulation of claims under the EPC 1973", see "Case law of the Boards of Appeal of the EPO", 6th edition 2010.