Under Art. 112(1)(a) EPC a board of appeal shall refer a question to the Enlarged Board of Appeal if it considers that a decision is required, in order to ensure uniform application of the law or because a "point of law of fundamental importance" arises. With the EPC 2000, the English wording was changed from "important" to "fundamental importance" in order to bring it into line with the French and German versions (see G 1/12, OJ 2014, A114).

Only questions on a specific point, not entire cases, may be referred to the Enlarged Board (e.g. T 184/91 of 25 October 1991 date: 1991-10-25, T 198/12). The Enlarged Board of Appeal is not a third instance within the EPO, but part of the second instance constituted by the boards of appeal (T 79/89, OJ 1992, 283). However, the Enlarged Board's answers to the referred points of law are binding on the referring board in respect of the appeal in question (Art. 112(3) EPC; see also J 8/07 of 1 July 2010 date: 2010-07-01).

The Enlarged Board of Appeal is not bound by the way the referring board formulated the question, and may redraft the referred question (see, for example, G 2/08 date: 2010-02-19, OJ 2010, 456, G 2/10, OJ 2012, 376, and G 1/13, OJ 2015, A42). The Enlarged Board does not consider referred questions narrowly, but in a way as to clarify the points of law which lie behind them (G 3/14, referring to G 2/88 and G 6/88, OJ 1990, 93 and 114).

The Enlarged Board of Appeal in petition for review proceedings under Art. 112a EPC is not a "Board of Appeal" within the meaning of Art. 112(1)(a) EPC that could initiate referral proceedings under that provision (R 7/08, R 1/11, R 7/12). The Disciplinary Board of Appeal has no power to refer questions to the Enlarged Board of Appeal either (D 5/82, D 7/82, D 9/91, D 30/05).

If a board is not empowered to decide a question, it is not empowered to refer that question to the Enlarged Board (T 1142/12).

Questions can be referred by a board either of its own motion or following a request from a party. If a board rejects a party's request for referral, it must give reasons in its final decision (Art. 112(1)(a) EPC). This was considered necessary to provide the parties with a certain guarantee, on the one hand, and to enable a certain degree of standardisation of the jurisprudence on the other (travaux préparatoires, BR/177/72, p. 31). Providing parties with a right of reference was, however, rejected (BR/168/72, p. 51).

The parties to the appeal proceedings are parties to the proceedings before the Enlarged Board (Art. 112(2) EPC). The Enlarged Board may invite the President of the EPO to comment on questions of general interest; the parties are entitled to submit their observations on the President's comments (Art. 9 RPEBA). Third parties may send written statements (amicus curiae briefs) to the Enlarged Board (Art. 10 RPEBA).