b) Public prior use 

As far the standard of proof to be applied is concerned, the boards' established legal practice is to apply as a rule the same standard of proof to prior public use objections as to other objections under Art. 100 EPC: the balance of probabilities. In cases of prior public use for which the evidence lies entirely within the sphere of the opponent the higher standard of proof "beyond any reasonable doubt" (also called in English "up to the hilt") applies (see T 472/92, OJ 1998, 161, and chapter III.G.4.3.2 "Public prior use" for more details of the case law in this area and on the implications of the "up to the hilt" standard of proof; on this latter point see e.g. T 2451/13).