In G 1/07 (OJ 2011, 134) the appellant had submitted that exclusions to patentability had to be construed narrowly according to Art. 31 and 32 of the Vienna Convention.

The Enlarged Board held that no general principle of narrow interpretation of exclusions from patentability which would be applicable a priori to the interpretation of any such exclusions can be derived from the Vienna Convention. Rather, the general rule in Art. 31, point 1, of the Vienna Convention that a treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose must apply to the exclusion clauses contained in the EPC in the same manner as to any other provision. If the interpretation of the provision concerned according to these principles of interpretation leads to the result that a narrow interpretation is the right approach then and only then is such restrictive meaning to be given to it.

In G 2/12 and G 2/13 the Enlarged Board came to the conclusion that whilst there is no general notion of an obligatorily restrictive construction of exceptions to patentability, for example, such as that adopted by the Court of Justice of the European Union (CJEU) when insisting on a narrow interpretation of exceptions to or derogations from fundamental EC Treaty principles embodied in the four freedoms (Judgment of 21 June 1974, C 2-74, Jean Reyners v. Belgian State, ECJ 1974, 631), such a narrow interpretation might well result from applying the general principles of interpretation to a specific provision with regard to specific legal and factual circumstances.

G 1/07 made reference to Opinion G 1/04, OJ 2006, 334 (point 6 of the Reasons). In that Opinion, the Enlarged Board stated – with reference to decisions of the boards of appeal having acknowledged the existence of such an a priori principle – that the "frequently cited principle", according to which exclusion clauses from patentability laid down in the EPC are to be construed in a restrictive manner, does not apply without exception. In that Opinion concerning the definition of the term diagnostic methods practised on the human or animal body, the Enlarged Board came to its conclusion that the said exclusion was indeed to be interpreted narrowly only after a thorough examination of the wording and the purpose of the exclusion clause concerned. The same approach was also taken in the Enlarged Board's decision G 2/06 (OJ 2009, 306). There, the Enlarged Board was concerned with the interpretation of the exclusion from patentability of biotechnological inventions relating to uses of human embryos for industrial or commercial purposes under R. 28(c) EPC (and the corresponding Art. 6(2) of the EC Directive on the legal protection of biotechnological inventions). The Enlarged Board made no reference to the existence of a principle of narrow construction of exceptions from patentability. Instead, as a method for interpreting the extent of the prohibition the Enlarged Board went directly to the rules of interpretation laid down in the Vienna Convention, i.e. it looked at the terms of the provision and its object and purpose (point 16 of the Reasons). No mention was made in that decision of any narrow or restrictive view which would have to be taken because the said prohibition was an exception to patentability. The Enlarged Board decided to proceed in the same way in G 1/07.