b) Article 123(1) EPC in conjunction with Rules 79(1) and 81(3) EPC as legal basis 

In T 755/96 the board held that the power of the opposition division to accept or refuse late-filed new facts or evidence was governed by Art. 114(2) EPC 1973, the discretionary power to refuse new requests for amendments by Art. 123 EPC 1973 and the corresponding implementing regulations, i.e. R. 57a EPC 1973 (R. 80 EPC) (see also T 1903/13, which cites Art. 123(1) EPC as the legal basis for the discretion of the boards in opposition appeal proceedings). Several recent decisions have likewise considered Art. 123 EPC (albeit in conjunction with R. 79(1) and 81(3) EPC) to be the legal basis for this discretion: T 966/17, R 6/19 and T 256/19.

In T 966/17 the board considered that the opposition division's discretion in deciding whether to admit amended claims followed in essence from Art. 123(1) EPC (first sentence) in conjunction with R. 79(1) and 81(3) EPC for the reasons set out below: Art. 123(1) EPC provided that a European patent application or a European patent could be amended in proceedings before the EPO in accordance with the Implementing Regulations. In opposition proceedings, R. 79(1) EPC allowed the patent proprietor to amend the description, claims and drawings within a period set by the opposition division. Later amendments, by contrast, were admissible only at the opposition division's discretion, as was clear from R. 81(3) EPC for instance ("shall, where necessary, be given the opportunity"). See also T 1081/20.

In R 6/19 the Enlarged Board held that the basis for an opposition division's discretion to admit or not admit claim requests was Art. 123(1) EPC. It observed that the first sentence states the general possibility to carry out amendments in patent applications and in patents, but only in accordance with the provisions of the Implementing Regulations (R. 81(3) EPC for opposition proceedings). It also noted that the second sentence of Art. 123(1) EPC explicitly provides applicants with a right to at least one opportunity to amend an application and remarked that, were the first sentence of Art. 123(1) EPC to mean that the patent proprietor or applicant always has the right to amend their patent or application, the second sentence of Art. 123(1) EPC would be redundant. The Enlarged Board pointed out that the right, found in the second sentence of Art. 123(1) EPC, to at least one opportunity to amend, does not extend to a patent proprietor in opposition proceedings, where the opposition division has the discretion, given in the first sentence of Art. 123(1) EPC, not to admit such requests. In such proceedings an opportunity to amend is to be given only where necessary (R. 81(3) EPC). The Enlarged Board saw no need to answer the question whether Art. 114(2) EPC, too, provides a basis for refusing requests.

In T 256/19 it was the board's view that discretion to disregard an amended version of a patent in inter partes proceedings could only emanate from Art. 123(1) EPC in conjunction with R. 79(1) EPC and/or R. 81(3) EPC and, in case of arranged oral proceedings, with R. 116(2) EPC.

In J 14/19 the Legal Board stated that Art. 123(1) EPC could serve as an additional legal basis besides Art. 114(2) EPC.