In some decisions it has been observed that new arguments first put forward at the oral proceedings without any reasonable explanation or justification are to be regarded as late filed and not admitted into the proceedings (T 1069/08, T 775/09, T 1621/09, T 810/12).
In T 1621/09 the board held that a new argument brought forward in appeal proceedings by a party which would have the effect of amending its case, even if the argument is based on evidence and facts already in the proceedings, can only be introduced into the proceedings at the discretion of the board of appeal by way of an amendment under Art. 13 RPBA 2007. The board, in the exercise of this discretion, decided however not to allow the appellant to amend its case, inter alia because the new argument amounted to a new way of putting the appellant's case on novelty and was raised at the last stage of the appeal, namely during oral proceedings.
In T 1069/08 it was only at the oral proceedings that the appellant (opponent) asked the board to be allowed to present its arguments on the lack of obviousness of the claimed subject-matter. This request was refused by the board. The appellant's statement of grounds of appeal did not include any argument regarding the obviousness of the claimed subject-matter. Hence, the introduction of this new argument at oral proceedings represented an amendment to the appellant's case (Art. 13(1) RPBA 2007).
In T 1761/10 the board also decided not to admit the new inventive step attack submitted at oral proceedings. The appellant's attack raised complex new issues and oral proceedings would have had to have been adjourned in order to give the board and the respondent sufficient time to address these issues (see also T 1226/12 and T 2602/12).
In T 775/09, the party as of right's second line of argument was based on a number of citations first referred to at the oral proceedings on appeal. The board observed that such an amendment to the party's case at this stage gave rise to combinations and facts of a complex nature which had not previously been addressed during the written proceedings. Therefore the board exercised its discretion under Art. 13(1) RPBA 2007 and refused to admit the new argument at such a late stage of the appeal proceedings.
In T 1019/13 a new inventive-step attack was made for the first time during the oral proceedings before the board. In the written proceedings, the opponents made more than ten different inventive-step attacks based on various different combinations of documents. It was already a heavy burden for the proprietor to prepare a defence addressing all these different attacks. In such a situation, the proprietor could not be expected to extend its preparation to cover yet more inventive-step attacks, based on new combinations of documents, which opponents might make during the oral proceedings.
In T 181/17 the board did not admit the new inventive step attack using D17 as closest prior art submitted at the oral proceedings. D17 was only referred to in the context of novelty. The board stated that novelty and inventive step were different grounds of opposition, and documents useful in attacking novelty were not necessarily the same as those that qualified as the closest prior art.
In T 647/15, by choosing to keep silent until the oral proceedings and make its arguments based on documents D10 and D11 only then, the opponent had surprised the board and the other parties, thereby undermining those parties' right to comment as appropriate in an adversarial procedure.
In T 1890/13 document D28 was initially filed with the notice of opposition. Thus, it was filed in due time within the meaning of Art. 114(2) EPC. However, it was discussed neither during the oral proceedings before the opposition division nor in the impugned decision. It was only at the oral proceedings before the board that the appellant argued for the very first time that D28 was extremely relevant for the assessment of inventive step. The board held that this new line of argument based on D28 was submitted at a very late stage in the overall proceedings. Therefore, the question of admitting the substantiated document D28 into the appeal proceedings was subject to Art. 13(1) and (3) RPBA 2007. The board refused the appellant's request that D28 be introduced into the appeal proceedings under Art. 13(1) RPBA 2007, for the following reasons: the late substantiation of D28 was not an appropriate and immediate reaction to unforeseeable developments in the proceedings, the teaching of D28 was not prima facie more relevant than the other prior art documents on file; admitting into the appeal proceedings such a new line of argument based on D28 would run counter to the principle of procedural economy and fairness.