EPO case law: If the opponent fails to respond, he acquiesces

For an opponent not to be adversely affected, the case law demands that the opponent has agreed to the maintenance of the patent in the corresponding version. As it follows from the context of the procedural provisions of the EPC, an opponent wishing to oppose the grant of a patent must state the grounds on which the patent should not have been granted. From this it follows for the appeal proceedings that an opponent does not oppose the maintenance of the patent in a certain version if he does not submit any grounds against this version which prejudice its maintenance. Only by asserting one or more of these reasons can the opponent claim that he does not agree with the patent in its granted or maintained version. Thus, if a new version is presented by the patent proprietor at the oral proceedings before the opposition division, the opponent can only be adversely affected under those grounds of opposition under Art 100 a)-c) EPC, which the opponent presented at the oral proceedings. If the opponent has not asserted any grounds for opposition at the oral proceedings, the appeal must be rejected as inadmissible (EPA-BoA 11 October 2017, T 0735/13).