In T 954/93 the appellant (opponent) had put forward objections to the patent on the basis of lack of novelty, which would have had to be demonstrated by means of experiments. It had not, however, carried out any tests on the ground that they would have been very expensive. The board considered the allegation unproven and refused to reverse the burden of proof. The fact that experiments would have been very expensive did not shift the burden of proof onto the patent proprietor.
In T 453/04 the opposition had been rejected, i.e. the grounds alleged pursuant to Art. 100 EPC had been found not to be substantiated. The board referred to the previous case law in T 667/94 according to which, in such cases, the burden of showing that the decision of the opposition division was incorrect remained with the appellant/opponent. The burden is not automatically shifted to the proprietor to show on appeal that the reasons for maintaining the patent were justified was not automatically shifted to the proprietor.
According to T 499/00, the burden of proof could not be reversed to rest with patentee in cases where – as opposed to the situation in T 585/92 – the patent had been revoked by the opposition division not on the strength of a real failure to disclose the information needed to reproduce the claimed subject-matter, but for reasons that the board elsewhere deemed erroneous.