b) Sufficient substantiation of grounds for opposition 

In T 623/18 the board guarded against a too strict approach. The board emphasised the purpose of the statement under R. 76(1) and (2)(c) EPC, as explained in G 9/91 and G 10/91 (OJ EPO 1993, 408 and 420), namely to define the extent and scope of the opposition and the legal and factual framework, within which the substantive examination of the opposition is in principle conducted, as well as to give the patentee a fair chance to consider his position at an early stage of proceedings. The board saw no basis for making admissibility of the opposition dependent on the assessment of substantive questions, in particular on whether an objection merely related to a lack of clarity or could support the ground for opposition under Art. 100(b) EPC. It was also a matter of substantive examination to characterise the person skilled in the art, for whom, according to Art. 100(b) EPC, the description should be sufficiently clear and complete, and for whom obviousness over the prior art was to be assessed according to Art. 100(a) EPC in combination with Art. 56 EPC.

In T 2037/18 the opposition division had rejected an opposition based on prior use as insufficiently substantiated and therefore inadmissible, stating in its reasons that no information had been presented to rebut the presumption that confidentiality was implicitly expected in a manufacturer-customer relationship in the period around the handover/acceptance of trains. The board did not share this view. It first stated that, under the rules on the burden of assertion and proof applicable in EPC proceedings, each of the parties had to present and prove the facts in their favour (T 219/83, T 270/90). It then explained that the sale of a ready-to-use object to a third party was the typical case of something being made publicly available (T 482/89), since the third party usually had an interest in using the object as they saw fit. Thus, when an object was sold to a customer, it and its identifiable technical features became publicly available on its handover to that buyer (positive fact) unless the buyer was bound by a confidentiality obligation (negative fact). Accordingly, it was for the opponent to assert and prove such a handover to a buyer (T 326/93), whereas it was for the patent proprietor to assert and prove that this buyer had been bound by any confidentiality obligation (T 221/91, T 969/90), as was reflected in the principle "negativa non sunt probanda", i.e. a negative need not be proved, recognised in the boards' case law (R 15/11, R 4/17). The board went on to observe that the burden of assertion and proof could shift but not until the party initially bearing it had produced prima facie evidence or argued a typical course of events supporting a presumption as to the facts (T 570/08). A patent proprietor's submissions could therefore place a secondary burden of assertion and proof on the opponent, but only from that point on ("ex nunc") and so without any bearing on what it was required to substantiate in its notice of opposition under the third point of R. 76(2)(c) EPC. The board considered that there was no need in the case in hand to rule on whether it would have decided differently if the opponent itself had asserted during the opposition proceedings circumstances giving rise to one of the presumptions in favour of a confidentiality agreement recognised in the boards' case law, since no such circumstances were involved here. In particular, nowhere in their case law had the boards recognised a presumption that manufacturers of rolling stock and railway companies generally undertook to maintain confidentiality as regards delivered and accepted vehicles.

In T 16/14 the opponent (appellant) had filed an author's copy of an article in a technical journal (E1) to substantiate its ground for opposition under Art. 100(a) EPC. The opposition division had considered this insufficient on the basis that it had not been proven that E1, the only document cited in this respect, had been published. The respondent contended that it had not been known at the time of filing of the opposition that E1 was an author's copy. The board rejected this line of argument. It could readily have been established whether there was any difference in content between the produced author's copy and the article actually published, as E1's publisher had at any rate been specified in such a way that such a check could have been performed without undue burden. Besides, the appellant had not only already offered in its notice of opposition to produce the actually published article but also gone on to do so (E1a). The board further found that document E1/E1a had been made available to the public before the priority date of the patent in suit (31 October 2006) and therefore concluded that the ground for opposition under Art. 100(a) EPC had been sufficiently substantiated.