o) New defence and belated substantiation of a defence 

(i) New defence vs elaboration on arguments already on file 

In T 1108/16 the respondent (patent proprietor) countered the inventive-step objection raised in the grounds of appeal only after receiving the communication under Art. 15(1) RPBA, by submitting arguments as to why taking the cited prior art documents together could not render the combination of features in claim 1 of its main request obvious. On the admissibility of these late-filed arguments, it contended that they had to be regarded as a natural elaboration on arguments in its reply, which already included a detailed analysis of the documents' content from which it directly followed that their teachings were essentially incompatible. The board, however, pointed out that, especially in adversarial opposition-appeal proceedings, it was essentially bound in its assessment of the factual and legal circumstances by the case made by each of the parties. Accordingly, it was not – and could not be – up to it to piece together itself from that case arguments a party had not expressly set out in defence of its patent. The new submissions in this case had to be regarded as an amendment.

(ii) Assertions containing new factual elements 

In T 2803/18 the board decided pursuant to Art. 13(2) RPBA not to take into account the respondent’s (patent proprietor’s) assertion of a distinguishing feature. Contesting that the feature was disclosed in D2 introduced a new factual element into the proceedings and therefore constituted an amendment to the respondent's appeal case. See also T 791/17.

In T 121/20, in order to counter the objection that claim 1 of the main request encompassed an embodiment which was not originally disclosed, the respondent (patent proprietor) invoked for the first time on appeal a different interpretation of a certain term in the claims. The board held that even if this new argument was submitted in the framework of the same objection and the same features, it amounted to a new interpretation of the claim being based on new facts (different passages in the description) and thus changed the respondent's case.

In T 203/20 auxiliary request 9 had been filed with the statement of grounds of appeal, but only during oral proceedings did the appellant (proprietor) argue that the subject-matter claimed was entitled to the priority claimed by the patent. The board held that these submissions consisted of both new allegations of fact as well as new arguments in law, and represented an amendment to the patent proprietor's case.

In T 19/20 a new line of defence against an objection under Art. 123(3) EPC was brought forward for the first time at the oral proceedings before the board. Whereas the respondent (patent proprietor) had previously argued that the deleted part was an added undisclosed feature without any technical meaning, it argued at the oral proceedings that the deletion of a feature did not change the scope of claim 1 because it was implicitly limited by this feature in view of the description. The board held that this new line of defence raised new legal and technical issues and thus constituted a change of the legal and factual framework of the appeal.

For a further decision discussing whether a new defence comprised a new allegation of fact and thus amounted to an amendment to the party's appeal case, see e.g. T 1303/18 (summarised above in chapter V.A.4.2.3p)).

(iii) New experimental data 

In T 2271/17 the respondent (patent proprietor) argued that the late-filed experimental data was fully in line with its position regarding inventive step set out earlier in written appeal proceedings and therefore not an amendment to its case. The board however clarified that by arguing that the experimental data demonstrated a specific effect, the respondent indicted that the data was relevant in the assessment of inventive step and the formulation of the objective technical problem. Consequently, the filing of the experimental data could only be understood as an amendment to the respondent's appeal case.

(iv) Belated substantiation of a defence 

In T 2752/19 the board considered that the new line of argument, brought forward by the appellant (applicant) during the oral proceedings before the board, went beyond a mere refinement of the arguments submitted in the statement of grounds of appeal. In these initial submissions the appellant had argued without further substantiation that D2 neither disclosed nor suggested the combined features of claim 1 of the sole request. Therefore, the new line of argument constituted an amendment to the appellant’s appeal case.