8.3. Skilled person – level of knowledge

Inventive step has to be assessed on the basis of the skilled person's knowledge before the priority or filing date (see (T 268/89, OJ 1994, 50; T 365/89).

The same level of skill has to be applied when, for the same invention, the two questions of sufficient disclosure and inventive step have to be considered (T 60/89, OJ 1992, 268; T 373/94, T 99/14, T 1861/16, see also chapter II.C.4.1 "The disclosure is aimed at the skilled person"). In T 694/92 (OJ 1997, 408) the board added that, although the same level of skill is applied for both Art. 56 and Art. 83 EPC 1973, the two starting points differ; for inventive step purposes, the skilled person knows only the prior art; for sufficiency of disclosure, he knows the prior art and the disclosed invention.

In T 426/88 (OJ 1992, 427) the board held that a book providing general teaching in a general technical field covering the invention's specific technical field was part of the general knowledge of a specialist in that specific technical field. When books, representing common general knowledge, described a basic general technical theory or methodology and exemplified the same with specific applications in certain technical fields only, these did not limit the general scope and relevance of such disclosures so as to exclude possible applications in other fields. The appellant had argued that the book, written in German, was not a general reference book consulted by experts in that field in Great Britain. The board, however, adhered to the definition of the state of the art given in Art. 54 EPC 1973, according to which no account was taken of the location at which the skilled person exercised his profession. It was also of the view that the language of publication alone could not be decisive for the admissibility of a technical book representing the common general knowledge of the skilled person (see also T 1688/08). In T 2058/18 the board found that the (technically) skilled person might be considered a multilingual person but not normally a linguist.

In T 632/10 the board pointed out that even if an invention happened to be obvious only for skilled persons of German nationality or residence, it would still lack an inventive step within the meaning of Art. 56 EPC 1973. The fact that the German Signature Law (SigV) was valid only within Germany thus had no bearing on its status as prior art or its relevance for the assessment of inventive step outside Germany.

In T 766/91 the board pointed out that information did not usually become common knowledge through publication in a given handbook or textbook; rather it appeared in handbooks or textbooks because it was already common knowledge. For this reason, publication in an encyclopaedia, say, could normally be taken as proof that the information was not only known but was common general knowledge. In T 378/93 the board added that the same applied to articles in scientific periodicals addressed primarily to qualified professionals and enjoying worldwide repute. In T 537/90 the board held that numerous publications in the specialist press over a fairly short time, reporting on meetings and research in a particularly active field of technology, could reflect common general knowledge in this field at that time.

In T 939/92 (OJ 1996, 309) it was explained that the state of the art could also perfectly well reside solely in the relevant common general knowledge, which, in turn, need not necessarily be in writing, i.e. in textbooks or the like, but might simply be a part of the unwritten "mental furniture" of the average skilled person. In the case of any dispute, however, the extent of the relevant common general knowledge had to be proven, e.g. by documentary or oral evidence.

In T 632/91 the board stated that evidence which did not comprise a comparison of the claimed subject-matter with the state of the art might nevertheless rebut a prima facie assumption that there existed some common general knowledge which would have allowed the skilled person to disregard structural differences in chemical compounds.

In T 984/15 the board recalled that the technical field and general knowledge associated with the notional skilled person within the meaning of Art. 56 EPC should be defined on the basis of the objective technical problem to be solved by that skilled person in the framework of the problem-solution approach. This was because the skilled person under Art. 56 EPC is the person qualified to solve the established objective technical problem (see e.g. T 32/81, OJ 1982, 225; T 422/93, OJ 1997, 25; T 1140/09; T 1523/11; T 1450/16).

In T 1601/15 the board held that the skilled person did not need prompting to apply their knowledge. It was not convinced by the argument that the skilled person would have had no reason to draw upon it. The skilled person did not need a reason to apply their knowledge. This knowledge formed, as it were, the technical background for any activities they performed and fed into all their decisions. In this regard, a distinction had to be made between the common general knowledge in the art and the teaching of specialist documents.

In T 206/83 (OJ 1987, 5) the board pointed out that normally patent specifications were not part of common general knowledge. In T 1540/14 the board held that the common general knowledge of the skilled person was not normally established on the basis of the content of patent documents (see also e.g. T 671/94).

It has been emphasised in several decision that the assertion that something was part of the common general knowledge needed only to be substantiated if challenged by another party or the EPO (see e.g. T 766/91, T 234/93 . Where an assertion that something was part of the common general knowledge is challenged, the person making the assertion must provide proof that the alleged subject-matter indeed forms part of the common general knowledge (T 766/91; T 939/92, OJ 1996, 309; T 329/04; T 941/04; T 690/06).