"Mixed" inventions are inventions having both technical and non-technical features, where "non-technical" relates to matter which under Art. 52(2) EPC is not to be regarded as an invention within the meaning of Art. 52(1) EPC (T 1543/06). In claims comprising technical and non-technical features, each feature has to be evaluated to see if, in the context of the invention, it contributes to the technical character of the claimed subject-matter, since this is relevant for assessing inventive step (Guidelines G‑II, 2 – November 2018 version).

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 (T 26/86, OJ 1988, 19; T 769/92, OJ 1995, 525; T 641/00, OJ 2003, 352; T 531/03; T 154/04, OJ 2008, 46; T 1784/06).

When assessing the inventive step of such a mixed-type invention, all those features which contribute to the technical character of the invention are taken into account. These also include the features which, when taken in isolation, are non-technical, but do, in the context of the invention, contribute to producing a technical effect serving a technical purpose, thereby contributing to the technical character of the invention. However, features which do not contribute to the technical character of the invention cannot support the presence of an inventive step (T 641/00). Such a situation may arise, for instance, if a feature contributes only to the solution of a non-technical problem, e.g. a problem in a field excluded from patentability (Guidelines G‑VII, 5.4 – November 2018 version).

In T 26/86 (OJ 1988, 19) the board held that an invention must be assessed as a whole. If it makes use of both technical and non-technical means, the use of non-technical means does not detract from the technical character of the overall teaching. The EPC does not ask that a patentable invention be exclusively or largely of a technical nature; in other words, it does not prohibit the patenting of inventions consisting of a mix of technical and non-technical elements even if the technical part is not the dominating part of the invention. The board, although allowing a mix of technical and non-technical features to be claimed, considered the technical part of the invention as the basis for assessing inventive step (see T 641/00, OJ 2003, 352, point 4 of the Reasons; see also T 209/91).

The inventive step requirement of Art. 52(1) and 56 EPC 1973 is assessed using the well-established problem-solution approach, which is fundamentally technical in nature (T 172/03). This requires analysis of the invention in terms of a technical solution to a technical problem. When applied to "mixed" inventions, such an approach must necessarily differentiate between an invention's technical and non-technical features.

According to the established case law, features of an invention that do not have a technical effect or do not interact with the remaining features of the invention so as to result in a technical functional contribution cannot be considered to contribute to an inventive step within the meaning of Art. 56 EPC. This is not only the case when the features themselves do not contribute to the technical character of the invention (T 641/00, OJ 2003, 352; T 258/03, OJ 2004, 575; and T 531/03; see also T 456/90, T 931/95, T 27/97, T 258/97, T 1121/02 and T 1784/06), but also when the features may in principle be qualified as being of a technical nature but do not have any technical function in the context of the claimed invention (T 619/02, OJ 2007, 63) (see for instance T 72/95, T 157/97, T 158/97, T 176/97). In addition, this is so regardless of whether the features are themselves obvious or not (see T 72/95, T 157/97, T 158/97 and T 176/97).

In T 641/00 (OJ 2003, 352), the board had already held thatfeatures of the invention which did not form part of the technical solution to the technical problem had to be disregarded in the assessment of inventive step (T 931/95, OJ 2001, 441); T 1121/02, T 1543/06, T 336/07, T 859/07, T 859/07). In T 531/03 the board confirmed the principles set out in T 641/00 and stated that, in the assessment of inventive step, features relating to a non-invention within the meaning of Art. 52(2) EPC 1973 (so-called "non-technical features") could not support the presence of an inventive step (see also T 1543/06). In T 258/03 (OJ 2004, 575), the board held that the invention was to be assessed by taking account only of those features which contributed to a technical character. The features that made a technical contribution therefore needed to be determined. In T 1543/06 the board stated that the principle as expressed in T 641/00 (OJ 2003, 352) could be also reformulated as follows: an invention which as a whole falls outside the exclusion zone of Art. 52(2) EPC 1973 (i.e. is technical in character) cannot rely on excluded subject matter alone, even if novel and non-obvious (in the colloquial sense of the word), for it to be considered to meet the requirement of inventive step (see also T 336/07).

The presence of an inventive step can only be established on the basis of the technical aspects of both the distinguishing features of, and the effects achieved by the claimed invention over the closest state of the art (T 641/00, OJ 2003, 352) (see also T 619/02, OJ 2007, 63). The presence of an inventive step cannot rely on excluded (non-technical) subject matter alone, however original it may be (see also T 336/07).

It is the established case law of the boards of appeal (see G 3/08 date: 2010-05-12, OJ 2011, 10; T 258/03, and T 424/03, T 313/10) that claimed subject-matter specifying at least one feature not falling within the ambit of Art. 52(2) EPC is not excluded from patentability by the provisions of Art. 52(2) and (3) EPC. Features which would, taken in isolation, belong to the matters excluded from patentability by Art. 52(2) EPC may nonetheless contribute to the technical character of a claimed invention, and therefore cannot be discarded in the consideration of the inventive step. This principle was already laid down, albeit in the context of the so-called "contribution approach", in one of the earliest decisions of the boards of appeal to deal with Art. 52(2) EPC, namely T 208/84 (point 4 ff. of the Reasons) (see also T 1784/06).

In T 258/03 (OJ 2004, 575) the board noted that, taking into account both the fact that a mix of technical and non-technical features may be regarded as an invention within the meaning of Art. 52(1) EPC 1973, and the fact that prior art should not be considered when deciding whether claimed subject-matter is such an invention, one compelling reason for not refusing subject-matter consisting of technical and non-technical features under Art. 52(2) EPC 1973 is simply that the technical features may in themselves turn out to fulfil all the requirements of Art. 52(1) EPC 1973. It is often difficult to separate a claim into technical and non-technical features, and an invention may have technical aspects which are hidden in a largely non-technical context. Such technical aspects may be easier to identify within the framework of the examination as to inventive step, which, in accordance with the jurisprudence of the boards of appeal, is concerned with the technical aspects of an invention. Thus, in addition to the restrictive wording of Art. 52(3) EPC 1973 limiting the applicability of Art. 52(2) EPC 1973, there may be practical reasons for generally regarding mixes of technical and non-technical features as inventions within the meaning of Art. 52(1) EPC 1973.

The methodology applied by the boards of appeal of the EPO in dealing with "mixed" inventions has been summarised in T 1543/06 (see also T 859/07).