The boards of appeal have been concerned with the assessment of inventive step in cases where the invention consisted of a mix of technical and non-technical features. Decision T 154/04 (OJ 2008, 46) analysed the case law relating to the patentability of inventions and summarised the main principles concerning mixed inventions as follows: for examining patentability of an invention in respect of a claim, the claim must be construed to determine the technical features of the invention, i.e. the features which contribute to the technical character of the invention. It is legitimate to have a mix of technical and "non-technical" features appearing in a claim, in which the non-technical features may even form a dominating part of the claimed subject matter. Novelty and inventive step, however, can be based only on technical features, which thus have to be clearly defined in the claim. Non-technical features, to the extent that they do not interact with the technical subject matter of the claim for solving a technical problem, i.e. non-technical features "as such", do not provide a technical contribution to the prior art and are thus ignored in assessing novelty and inventive step. Finally, for the purpose of the problem-and-solution approach, the problem must be a technical problem which the skilled person in the particular technical field might be asked to solve at the relevant priority date. The technical problem may be formulated using an aim to be achieved in a non-technical field, and which is thus not part of the technical contribution provided by the invention to the prior art. This may be done in particular to define a constraint that has to be met (even if the aim stems from an a posteriori knowledge of the invention).

These principles have indeed a clear and consistent basis in the EPC and in the case law of the boards of appeal and the Enlarged Board of Appeal, in particular. In this connection, the Enlarged Board of Appeal noted in G 3/08 date: 2010-05-12 (OJ 2011, 10) that it was not aware of any divergence in this case law, suggesting that the boards were in general quite comfortable with it, and concluded that it would appear that the case law had created a practicable system for delimiting the innovations for which a patent may be granted (see also T 116/06, T 1769/10).