8.3.4 Common general knowledge in general

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).

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 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.

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).

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 1520/19 the board held that it was appropriate, at least until the skilled person's qualifications were challenged, that in proceedings before the EPO the skilled person was often left undefined as long as their skills and knowledge were implied by the circumstances or the reasoning provided. It was in most cases pointless to fix the academic degree of the skilled person, unless attributing any specifically relevant, and controversial skill or common general knowledge to the skilled person depended on such detail. What exactly it required to establish any controversial qualification of the skilled person would depend on the case at issue. In the case in hand the board doubted that the qualification "Ph.D." level provided a practicable definition of a skilled person, and considered that appreciation of the application was possible for a person with the relevant practical experience in the art as proposed by the appellant.