T 1843/09 of 06.06.2012

The prohibition of reformatio in peius as far as it entails a procedural limitation of the proprietor's liberty to change by way of amendments the scope of protection sought prevails "in principle" (G 4/93) until the final settlement of the opposition case and, therefore, also in any proceedings, including further appeal proceedings, subsequent to a remittal under Article 111 EPC (point 2.3.1 of the reasons).

It is clear from G 1/99 that exceptions from the principle of the prohibition of reformatio in peius are a matter of equity in order to protect the non-appealing proprietor against procedural discrimination in circumstances where that prohibition would impair the legitimate defence of its patent. Therefore, exceptions from the prohibition of reformatio in peius are not limited to the situation specifically dealt with in G 1/99, where an error of judgment by the opposition division occurred concerning an amendment introduced into the version of the patent as maintained by the decision under appeal (point 2.4.4 of the reasons).