Under Art. 113(1) EPC the decisions of the EPO may only be based on "grounds or evidence" on which the parties concerned have had an opportunity to present their comments. "Grounds or evidence" are to be understood as meaning the essential legal and factual reasoning on which the EPO has based its decision (T 532/91, T 105/93, T 187/95, T 1154/04, T 435/07, T 1898/11). In T 951/92 (OJ 1996, 53) the board ruled that the term "grounds or evidence" should not be narrowly interpreted. In the case in point, which related to examination proceedings, the board held that the term was to be understood as referring to the legal and factual reasons leading to refusal of the application, and not in the narrow sense of a requirement of the EPC.
In T 375/00 the appellant/opponent considered that the technical problem mentioned by the opposition division in its decision was different from that discussed in the preceding proceedings. The board held that the appellant's right to be heard had not been violated, because the definition of the objective problem was part of the arguments, not part of the grounds as specified in Art. 113(1) EPC 1973.
In T 33/93 the board stated that the citation of a board of appeal decision for the first time in the decision under appeal was not a fresh ground or piece of evidence within the meaning of Art. 113(1) EPC 1973, but a mere repetition of arguments, since it only confirmed the position duly brought to the appellant's attention.
In T 990/91 the board held that since there had been no need for the examining division to put forward the new argument - which was supererogatory and incidental - in order to refuse the application, the lack of opportunity to reply to it could not be considered to be a violation of the right to be heard.
In T 587/02 the board saw no fundamental objection to citing in the decision of an examining division an IPER from an International Preliminary Examining Authority other than the EPO, provided that it constituted a reasoned statement (as required by R. 51(3) EPC 1973) using language corresponding to that of the EPC. In the case of an inventive step objection, that would require a logical chain of reasoning which could be understood and, if appropriate, answered by the applicant. Since the IPER in this case did not fulfil these requirements, the board held that the applicant's right to be heard had been violated.
In T 1634/10 the examining division had issued a reasoned communication setting out its objections in the light of two prior art documents, to which the appellant responded with a new claim and new arguments as to why the examining division had been wrong in its interpretation of the documents. Refusing the application, the examining division held that the amendments submitted by the appellant were not substantial. The board held that the examining division had introduced neither new grounds of refusal nor new evidence. The mere fact that the examining division had not agreed with the submission of the appellant did not amount to a breach of the right to be heard.