Where a written disclosure was published which was based on an oral disclosure at a public conference held some years earlier, it could not as a rule be assumed that the written disclosure was identical to the oral disclosure. Additional circumstances had to be put forward and proven to justify that conclusion (T 153/88). In T 86/95, the board assumed that the disclosures were identical since it was highly unlikely that the speaker would have passed over such a salient feature at the conference.
In T 348/94 the board confirmed that a written publication allegedly based on a paper previously read at a public meeting held some time earlier (in this case ten months) could not be assumed to be identical to what was orally disclosed, and might contain additional information. As to the extent of the oral disclosure, the burden of proof remained with the opponent.
In T 1212/97 the opponent had submitted that the invention had been made available to the public at a lecture given some days before the priority date to an audience of some 100 to 200 persons. The question to resolve was whether there was any safe and satisfactory evidence regarding the content of what had been made available to the public at the lecture.
The board did not consider evidence from the lecturer alone to be satisfactory evidence as to what had been made available to the public at the lecture. Even an audio or video tape recording made of the lecture, unless publicly available, would have to be treated with caution, if several hearings or viewings were necessary to extract all the information. Information appearing in each of the contemporary written notes made at the lecture by at least two members of the audience could usually be regarded as sufficient, whereas information in the notes of a single member of the audience might be inadequate, as it reflected the thoughts of the listener rather than solely the content of the lecture. If the lecturer read his lecture from a typescript or manuscript, or the lecturer wrote up his lecture subsequently, and the lecture was subsequently published in that form as part of the proceedings, then the written version might be taken as some evidence of the contents of the lecture, though with some caution as there would be no guarantee that a script was completely and comprehensibly read, or that a write-up had not been amplified. Most useful would be a handout given to the public at the lecture, containing a summary of the most important parts of the lecture and copies of the slides shown. None of those types of evidence were available in this case. The board was also forced to conclude that there was no safe and satisfactory evidence that the information conveyed in the lecture could be treated as having been made publicly available. The lecture had undoubtedly been given, but the board was not satisfied on the balance of probabilities, let alone beyond reasonable doubt, that the information provided went beyond what was already known in the art (see also T 1057/09).