In other decisions, the boards have ruled that a fact on the basis of which a case against novelty has been made has to be proved “beyond reasonable doubt” or “up to the hilt” (see e.g. T 313/05, T 782/92, T 97/94, OJ 1998, 467; T 848/94, T 472/92, OJ 1998, 161; and, in particular, T 750/94, OJ 1998, 32) (cf. T 1313/05).
In T 1553/06 the board regards the terms "beyond reasonable doubt" and the more colloquial term "up to the hilt" as being equivalent.
T 313/05 concerned the revocation of a granted European patent. The board stated that to base a revocation decision on the mere balancing of probabilities as to what might have occurred would be difficult to reconcile with the need for reliability in the decisionmaking procedures of the EPO, which was of utmost importance for users of the patent system as well as the general public. Thus, the public availability of the document at issue before the priority date of the patent in suit could only be regarded as established if, in view of the evidence, the board did not entertain any reasonable doubt in this respect (see also T 1335/05).
In T 738/04 the board noted that it is the established practice of the boards of appeal to apply the criterion of "absolute conviction" rather than the "balance of probabilities" in cases of prior public use for which the evidence lies entirely within the sphere of the opponent (see T 472/92, OJ 1998, 161, later reiterated in decision T 97/94 (OJ 1998, 467). This implies not only that the reasoning referred to by the appellant should be complete and conclusive but also that all facts supporting that reasoning be fully substantiated by corresponding evidence. This requirement is the consequence of the principle according to which parties representing opposite interests should be given equally fair treatment and derives from the contentious character of the post-grant opposition proceedings (see G 9/91, OJ 1992, 408). The board observed that, usually, the only possibility for a patentee who played no part in the alleged prior use is to take issue with the conclusive nature of the adduced evidence and consequently of the reasoning to which it gives rise; the unbalanced factual situation resulting from the unilateral access of the opponent to the available evidence is then compensated by the severe legal requirement developed by the case law that such prior use should be established beyond any reasonable doubt.
The board found that it was essential for the opponent to decide, when filing the notice of opposition or, at the latest, when filing the statement setting out the grounds of appeal, on which prior use the objection against the granted patent would be based. In a situation like the one at issue, in which the elaboration of a norm led to a multiplicity of factual situations possibly each constituting on its own a prior use (various printed versions of the norm, multiplicity of meetings, public enquiry, etc.), the opponent should, from the outset of the opposition proceedings or ensuing appeal proceedings, have identified those situations which for it would have the highest chance of success, i.e. those situations in respect of which he would be able to produce evidence complete enough to support the desired conclusion. In the opinion of the board, it would have been unfair to allow the appellant in the course of inter partes proceedings to extend the case originally put forward in relation to one specific situation to other situations, even if these situations arose in the framework of one and the same general elaboration process.
In T 990/09 the evidence on file consisted of two product information web pages. The appellant had argued that, in this case, the ‘up to the hilt’ standard of proof should be applied rather than the standard of the balance of probabilities. The board disagreed and held that the ‘up to the hilt’ standard, which had first been developed in decision T 472/92 was to be applied to cases of public prior use where practically all the evidence in support of an alleged public prior use lay within the power and knowledge of the opponent(s).
T 1416/10 concerned the public prior use of a washing machine manufactured and sold by the patent proprietor under model number WD-R100C. The board noted that, although there was no proof on file that the specific washing machine had indeed been available to the public prior to the relevant date of the patent in suit, notwithstanding that it was highly unlikely that this specific machine had remained with the manufacturer for more than one month before being delivered for sale to a distributor, the evidence submitted by the opponent allowed the conclusion to be drawn beyond any reasonable doubt that washing machines with the model number WD-R100C had been publicly available to the distributors for public sale prior to the relevant date of the patent in suit.
For more details regarding proof in connection with public prior use, see also Chapter "Law of evidence".