Where an assertion that something is common general knowledge is challenged, the person making the assertion must provide proof that the subject-matter in question is in fact common general knowledge (T 438/97, T 329/04, T 941/04, T 690/06). In the case of any dispute as to the extent of the relevant common general knowledge this, like any other fact in contention, has to be proved, for instance by documentary or oral evidence (T 939/92, OJ 1996, 309, see also T 766/91, T 1242/04, OJ 2007, 421; T 537/90, T 329/04 and T 811/06). The proof is regularly supplied in citing literature (T 475/88). According to T 766/91 and T 919/97, evidence of general technical knowledge need be submitted only if the latter’s existence is disputed.
In T 1110/03 (OJ 2005, 302), the board stated that when evaluating evidence relating to the issues of novelty and inventive step it was necessary to distinguish between a document alleged to be part of the state of the art within the meaning of Art. 54(2) EPC 1973 - in the sense that the document itself was alleged to represent an instance of what had been made available to the public before the priority date of the opposed patent - and a document which was not itself part of the state of the art, but which was submitted as evidence of the state of the art or in substantiation of any other allegation of fact relevant to issues of novelty and inventive step. Only a document of the first kind could be disregarded on the sole ground that it was post-published; documents of the second kind did not stand or fall by their publication date even on issues of novelty and inventive step. Similarly a technical review article is by definition an account of the common general knowledge in the art prior to its own publication date – which could bear inter alia on the issue of enabling disclosure of a prepublished document and hence on the novelty of claimed subject-matter (T 1625/06, T 608/07, T 777/08).
In T 608/07 the respondent tried to query the relevance of D6 because it was published after the priority date of the patent in suit. The board stated that D6 related to published course material of a university and to subject-matter well known in the art for many years. Hence, albeit published after the priority date of the patent in suit, D6 provided indirect evidence for common general knowledge.