d) Whether the amendment is detrimental to procedural economy 

In T 1684/17 the board did not admit a new objection of lack of inventive step, which was based on a newly filed document which the appellant alleged had only become known to it in parallel appeal proceedings. The objection concerned the subject-matter of claim 1 of the patent as granted and, in the board's view, should already have been raised by the opponent in the course of the opposition proceedings. The opponents' approach was inconsistent with the principle of procedural economy that applied to all parties to the proceedings and therefore also inconsistent with the principle set out in Art. 12(6), second sentence, RPBA. The prima facie relevance claimed by the appellant was not a decisive criterion to be taken into account when applying Art. 13(1) RPBA. On this last point, see also chapter V.A.4.4.6c).

Likewise in T 140/15, T 2227/15, T 154/16, T 1117/16, T 1217/17 and T 552/18 the boards, exercising their discretion under Art. 13(1) RPBA, concluded that admitting late submissions would (among other things) be inconsistent with the need for procedural economy and did not admit them into the proceedings.

By contrast, the board in T 553/22 admitted into the proceedings the opponent's reply to the statement of grounds of appeal, which was received 6 minutes after the expiry of the time limit set forth in Art. 12(1)(c) RPBA, as it did not prevent the board from considering the complete case of all the parties, nor seemed to be a tactical abuse of procedure, nor was contrary to procedural economy.