In T 305/08 the appellant (opponent I) had filed an appeal against the decision of the opposition division to reject the opposition. Two separate interventions were subsequently filed (by opponents II and III), which also raised fresh grounds of opposition under Art. 100(c) EPC 1973. The board stated that the term "any third party" in Art. 105(1) EPC could not be given an interpretation other than that each party had to be a separate legal entity and that it was irrelevant whether they belonged to the same group of companies. Nor was allowing the interventions tantamount to allowing the appellant to late-file oppositions via opponents II and III under its control and thus introduce new evidence. The interventions were therefore admissible.

In T 384/15 two interventions were filed in the appeal procedure by different legal entities, both belonging to the same company. The respondent (patent proprietor) argued that there was credible evidence that the opponent was acting as a straw man on behalf of the company to which also the two interveners were inextricably linked. The board considered that there was no question that the interveners were third parties within the meaning of Art. 105(1) EPC, i.e. different legal entities, with respect to the opponent (appellant) regardless as to whether or not one of the interveners was the principal instructing the opponent (G 3/97, OJ 1999, 245). The board also rejected the argument that there had been an attempt by the opponent and the interveners to circumvernt the law by abuse of process, since there was no proof that the opponent had acted directly on behalf of one of the interveners (T 305/08).