According to Art. 101(2) and (3)(a) EPC (former Art. 102(1) to (3) EPC 1973) a decision on an opposition to a European patent can involve revocation of the patent, rejection of the opposition or maintenance of the patent as amended, the latter requiring the publication of a new European patent specification. Under R. 82(2) EPC (former Art. 102(3)(b) EPC 1973) a prerequisite for maintenance of the patent as amended is that the printing fee be paid. With these regulations in mind, the EPO very early on adopted the device of an interlocutory decision, for which there is no express provision, in order to establish in the first place the text of the amended specification. Only after this interlocutory decision has come into force are the fee for printing and a translation of the claims in the other official languages requested pursuant to R. 82(2) EPC (former R. 58(5) EPC 1973). Once these requirements have been fulfilled what is then a non-appealable final decision on maintenance of the patent as amended is given and the new patent specification is published.
A decision to maintain the European patent - even an interlocutory decision - can of course only be given if there is a text "submitted or agreed" by the patent proprietor pursuant to Art. 113(2) EPC 1973. In that connection R. 82(1) EPC (Art. 102(3)(a) EPC 1973) states that it must be established, "in accordance with the provisions of the Implementing Regulations", that the patent proprietor approves the text. It has accordingly been standard practice for the EPO's opposition divisions always to proceed in accordance with the relevant R. 82(1) EPC (R. 58(4) EPC 1973) even where the text has already been "submitted or agreed" by the patent proprietor during the proceedings and rejected by the opponent.
The long-established practice of the EPO of delivering interlocutory decisions subject to appeal when a patent is maintained as amended was described in detail by the Enlarged Board of Appeal in G 1/88 (OJ 1989, 189).
Prior to the decision of the Enlarged Board of Appeal, it had been held in T 390/86 (OJ 1989, 30) that Art. 102(3) EPC 1973 and R. 58(4) EPC 1973 did not preclude that an opposition division could, in the course of opposition proceedings, make a (final) interlocutory decision in respect of a substantive issue raised by the opposition, before the sending of any R. 58(4) EPC 1973 communication. What was precluded by R. 58(4) EPC 1973 was that the opposition division should "decide on the maintenance of the European patent" in an amended form without first informing the parties of the amended text in which it was intended to maintain the patent and inviting their observations. However, neither Art. 102(3) EPC 1973 (now Art. 101(3)(a) and R. 82 EPC) nor R. 58(4) EPC 1973 precluded an opposition division from giving decisions on substantive issues in the opposition before sending a communication under R. 58(4) EPC 1973, and before "deciding to maintain the patent in amended form". For example, an opposition division could during the course of an opposition make a (final) interlocutory decision (either orally or in writing) that a particular proposed amendment contravened Art. 123 EPC. Similarly, in the board's view, an opposition division could make a (final) interlocutory decision during the course of an opposition that the main claim, for example, of the opposed patent could not be maintained. Such a substantive interlocutory decision was not a decision actually to maintain the patent in amended form, but was preliminary to such a decision. The taking of such substantive interlocutory decisions during the course of opposition proceedings was desirable both in order to move the proceedings forward towards a conclusion, and, in appropriate cases as envisaged in Art. 106(3) EPC 1973 (now Art. 106(2) EPC), to allow a party to appeal such an interlocutory decision before the opposition proceedings were terminated. It was further held that in a case where a final substantive decision had been given, an opposition division had no power thereafter to continue examination of the opposition in relation to the issues which were the subject of that decision, either under R. 58(5) EPC 1973 (now R. 82(2) EPC) or at all. Further submissions from the parties relating to such issues were inadmissible.
In T 89/90 (OJ 1992, 456) the opponents had lodged objections to an interlocutory decision which maintained the patent as amended. The board observed that the EPC contained no general rules as to when an interlocutory decision could or should be delivered. The relevant department therefore had to use its discretion in judging whether an interlocutory decision was appropriate in an individual case or whether the matter could only be settled in a decision terminating proceedings. This involved weighing up various considerations such as whether an interlocutory decision would accelerate or simplify the proceedings as a whole (clarifying a disputed question of priority, for example, could be of key importance for the form and length of the subsequent proceedings) and clearly also included the issue of costs. In the board's view, it was clear that the established practice of delivering appealable interlocutory decisions under Art. 106(2) EPC (Art. 106(3) EPC 1973) where a patent was maintained as amended was based on the weighing up of such cost aspects. The board concluded that this practice was both formally and substantively acceptable.