Under Art. 109(1) EPC, in ex-parte proceedings the department whose decision is contested must rectify its decision if it considers the appeal to be admissible and well-founded. Inter-partes proceedings are excluded from rectification. However, this does not prevent the department of first instance rectifying its decision where it erroneously revokes, on grounds of non-compliance, a patent it had decided to maintain in amended form (see T 168/03). On expiry of the three-month period under Art. 109(2) EPC 1973, the department of first instance whose decision is contested ceases to be responsible for the matter. Rectification of the decision is then no longer possible (T 778/06).

Art. 109(1) EPC provides an exception to the principle of general devolutive effect of the appeal, in order to allow an interlocutory revision. This exception has to be construed narrowly in connection with the interlocutory revision, and not as a broader entitlement for the department of first instance to decide whether an appeal is admissible (T 1973/09) (see also T 473/91 date: 1992-04-09, OJ 1993, 630, T 808/03 of 12 February 2004 date: 2004-02-12).

In T 638/01 a form was wrongly filled in and the appeal was sent by the formalities officer acting for the opposition division directly to the boards of appeal, bypassing the procedural step prescribed by Art. 109(1) EPC, viz. consideration for interlocutory revision. The board pointed out that since the granting of interlocutory revision in an appropriate case is mandatory, it followed a fortiori that considering a case for interlocutory revision in circumstances where the latter is possible is itself a mandatory procedural step. Since, however, the legislative purpose of Art. 109 EPC is overall procedural economy, it made no sense for the board to remit the case to the department of first instance for performance of this omitted step.