(1) In the event of an opposition to a European patent being filed, any third party who proves that proceedings for infringement of the same patent have been instituted against him may, after the opposition period has expired, intervene in the opposition proceedings, if he gives notice of intervention within three months of the date on which the infringement proceedings were instituted. The same shall apply in respect of any third party who proves both that the proprietor of the patent has requested that he cease alleged infringement of the patent and that he has instituted proceedings for a court ruling that he is not infringing the patent.
(2) Notice of intervention shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. Thereafter the intervention shall, subject to any exceptions laid down in the Implementing Regulations, be treated as an opposition.
74See decisions of the Enlarged Board of Appeal G 4/91, G 1/94 (Annex I).