Evidence of a written disclosure
During examination, the burden of proof lies with the Examiner (Guidelines G-IV 7.5.3).
If one of the Examiner’s arguments is that “it is common general knowledge to the person skilled in the art,” and the applicant disputes this, the Examiner must prove it with documents (Guidelines G-VII 3.1).
Evidence of an Internet citation
When citations are Internet pages, the standard level of proof to be applied is: the balance of probabilities (T286/10, T2339/09 and T990/09 or T2227/11).
The proprietor bears the burden of casting sufficient doubt to rebut this presumption, beyond merely invoking a general lack of reliability of the website.
This standard of proof is much lower than the level once required by certain decisions: beyond all reasonable doubt (T1134/06).
Evidence of an oral disclosure
Principle
The evidence provided must be examined in a highly critical and strict manner (Guidelines E-IV 4.3), and the certainty of the examining/opposition division must go beyond all reasonable doubt (T97/94, since all evidence relating to public prior use is in the possession of the opponent).
Case of conference minutes
Some consider that conference minutes accurately reflect the presentations given (Guidelines G-IV 1 and Guidelines G-IV 7.4) until the applicant disputes them with legitimate reasons. At the opposition stage, the opponent must provide evidence to the contrary.
However, if the minutes are published more than 6 months after the conference, the accuracy of these minutes may be called into question (T153/88 and T384/94).
Case of the lecturer’s testimony
Evidence of an oral disclosure cannot be provided by having the lecturer testify (T1212/97 and Guidelines G-IV 7.4), as the lecturer is in a very different position from the various parties (e.g., the disclosure may have seemed clear to them, while the audience may not have understood anything).
Similarly, it is unlikely that the lecturer will remember everything they said several years later (T843/15).
Case of the presentation material (PowerPoint)
One cannot simply assume that an oral disclosure exactly matches its written support (T843/15).
If a lecturer gives an oral presentation using slides, this document may establish a presumption of the presentation’s content, but the document alone is not sufficient to guarantee that the content of the slides was fully presented and, if so, in an intelligible manner.
To determine what information was actually disclosed to the public during an oral disclosure, it is therefore generally necessary to produce additional evidence, such as statements or written notes from the audience or a handout distributed to the public.
Evidence of prior use
The standard of proof expected for evidence of prior use is “beyond reasonable doubt” (T97/94) when this evidence is in the hands of the opponent.
However, if the evidence is provided by a witness who is not within the immediate sphere of the opponent (e.g., an independent supplier, T734/18), then the balance of probabilities may apply.