Under Art. 101(1) and Rule 79(1), the examination as to whether the European patent can be maintained can only be performed if at least one admissible opposition has been filed. This means that the opposition division has to refrain from commenting on the substantive merits of the opposition when expressing an opinion on its inadmissibility if there is no further admissible opposition (see T 925/91). Opposition proceedings are terminated if all notices of opposition filed against a European patent have been rejected as inadmissible and the last decision in this respect has become final. This will be communicated to the parties.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/d_iv_4.htm
Date retrieved: 17 May 2021