2.4.2 Intervention in appeal proceedings

In G 1/94 (OJ 1994, 787) the Enlarged Board concluded that intervention of the assumed infringer under Art. 105 EPC 1973 was admissible during pending appeal proceedings and could be based on any ground for opposition under Art. 100 EPC. The term "opposition proceedings" was not restricted to the department of first instance but could also refer to such proceedings at second instance. Intervention during pending appeal proceedings was therefore admissible (see also T 694/01). A notice of intervention filed during the two-month period for appeal has no legal effect if no appeal is filed (G 4/91, OJ 1993, 707). See also T 1286/23.

In T 694/01 the board found that intervention depended on how far the opposition or appeal was still pending. An intervener could not challenge issues on which a final decision had already been taken (in earlier appeal proceedings). For a similar situation where the intervention was filed during the opposition proceedings following a remittal, see T 2328/22 in this chapter III.P.2.4.1.