A disclosure destroys novelty only if the teaching it contains is reproducible. Subject-matter described in a document can only be regarded as having been made available to the public, and therefore as comprised in the state of the art pursuant to Art. 54(1) EPC, if the information given therein to the skilled person is sufficient to enable him, at the relevant date of the document (see Guidelines G-VI, 3), to practise the technical teaching which is the subject of the document, taking into account also the general knowledge at that time in the field to be expected of him (see T 26/85, T 206/83 and T 491/99). (Guidelines G-VI, 4 - version 2012).
In T 206/83 (OJ 1987, 5), in particular, it was found that a document (in this case, a copending European application) did not effectively disclose a chemical compound, even though it stated the structure and the steps by which it was produced, if the skilled person was unable to find out from the document or on the basis of his common general knowledge how to obtain the required starting materials or intermediates. Information which could only be obtained after a comprehensive search was not to be regarded as part of the common general knowledge. This need for an enabling disclosure was also in conformity with the principle expressed in Art. 83 EPC 1973 for patent applications which had, accordingly, to "disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art". The requirements as to the sufficiency of the disclosure were, therefore, identical in all these instances.
For selection inventions the requirement of a reproducible disclosure also plays a significant role. In T 26/85 (OJ 1990, 22) the board pointed out that anything comprised in the state of the art could only be regarded as having been made available to the public in so far as the information given to the person skilled in the art was sufficient to enable him to practise the technical teaching which was the subject of the disclosure, taking into account also the general knowledge in the field to be expected of him. In this particular case, the ranges of a certain parameter as defined in the claim fell within the broader ranges stated for the same parameter in a prior art document. The board considered that a realistic approach, when assessing the novelty of the invention under examination over the prior art in a case where overlapping ranges of a certain parameter existed, would be to consider whether the person skilled in the art would, in the light of the technical facts, seriously contemplate applying the technical teachings of the prior art document in the range of overlap; if it could be fairly assumed that this would be the case, it had to be concluded that no novelty existed. Such was not the case in the matter under consideration, since there existed in the prior art a reasoned statement clearly dissuading the person skilled in the art from using the range under a certain value, and the range of overlaps was under this value; the claimed range was therefore considered novel (see also T 255/91).
In T 447/92 the board held that the cited document did not disclose when or how far a movable piece in the claimed invention (an air circuit breaker) moved, or the way in which it worked to prevent the spring-back of a lever. No relative movement was described or shown in the drawings and it was a matter of conjecture as to the manner in which the relevant parts co-operated. The board found that it might have been obvious to a skilled person that the notch could co-operate with the shaft in the manner defined in the claims of the patent in suit, but that this only meant that the disclosure took him close enough to do the rest himself. It did not mean that the document took the skilled person all the way to the present invention. Thus, the features of the air circuit breaker according to claim 1 of the application were not unambiguously derivable from the drawings of an earlier European patent application.
In T 310/88 the board of appeal had to consider a discrepancy between what actually happened in practice when carrying out a technical teaching in a prior document according to the letter of its description, and what this prior document said would happen. The board held that the invention was novel over the prior document because the latter did not contain a sufficiently clear teaching for that conclusion not to be reached (see T 23/90).
In T 491/99, the board held that an earlier patent, which used terminology which at first sight was suggestive of the product invention claimed, was not in fact a prejudicial disclosure if a skilled person could actually only make the product in question later, from the process and machine described for the first time in the European patent in suit.
In T 1437/07 the board pointed out that a disclosure in a prior art document is novelty-destroying only if the teaching it contains is reproducible. This need for an enabling disclosure is in conformity with the principle expressed in Art. 83 EPC. Thus, the requirements of sufficiency of disclosure are identical for a prior art document and a patent. The board followed the principles developed by the case law in the framework of the evaluation of the requirements of Art. 83 EPC in the case of a medical use, i.e. that the skilled person should not only be able to carry out the teaching of the prior art document, but it should also be credible that the effect at issue - here, relief of pain - has been achieved (see also T 491/08).