Examination of the admissibility of the objection may be subject to the prohibition of reformatio in peius

If the opponent is the sole appellant against an interlocutory decision maintaining a patent in amended form, an objection of the patent proprietor (as respondent) related to the inadmissibility of the opposition is subject to the principle of the prohibition of reformatio in peius. In such a procedural situation, the Board of Appeal is prohibited from ordering the maintenance of the patent as granted due to the inadmissibility of the opposition (EPO Board of Appeal 21.6.2022, T 882/17).