b) Legal bases in the Rules of Procedure of the Boards of Appeal 

The Rules of Procedure of the Boards of Appeal (RPBA) lay down precise provisions on later amendments to a party's case which, in particular, explicitly leave it to the board's discretion whether to admit them (regardless of whether they relate to facts, objections, evidence or requests). The RPBA were thoroughly revised in 2019, with the new version entering into force on 1 January 2020 (this version is hereinafter referred to as "RPBA 2020", published in OJ 2019, A63 and republished in OJ 2021, A35 with Art. 15a RPBA 2020; on the RPBA generally, see also chapter V.A.1.2.; on the transitional provisions, see chapters V.A.4.3.2, V.A.4.4.2 and V.A.4.5.2).

Under Art. 12(2) and (4) RPBA 2020, the boards have discretion not to admit an amendment to the case made by a party at first instance or, more precisely, not to admit submissions on appeal which are not directed to requests, facts, objections, arguments or evidence on which the decision under appeal was based and for which the party has not demonstrated that they were admissibly raised and maintained at first instance. In addition, Art. 12(6) RPBA 2020, in a similar way as Art. 12(4) RPBA 2007 before it, explicitly refers to the boards' discretion not to admit requests, facts, objections or evidence which were not admitted in the first-instance proceedings (first sentence) or which should have been submitted or were not maintained in those proceedings (second sentence). Such submissions are not to be admitted unless the decision not to admit them at first instance suffered from an error in the use of discretion or the circumstances of the appeal case justify admitting them. For more detail on these provisions and how they have been interpreted in the case law, see chapter V.A.4.3. "First level of the convergent approach – submissions in the grounds of appeal and the reply – Article 12(3) to (6) RPBA 2020".

Under Art. 13(1) RPBA 2020, the boards have discretion whether to admit amendments to a party's appeal case after it has filed its statement of grounds of appeal or reply. The criteria for exercising this discretion are similar to those applied under Art. 13(1) RPBA 2007 and codify the case law on that earlier provision (see e.g. T 634/16, T 700/15). The case law on Art. 13(1) RPBA 2020 is reported in chapter V.A.4.4. "Second level of the convergent approach – submissions made after filing of grounds of appeal or reply – Article 13(1) RPBA 2020".

Art. 13(2) RPBA 2020 provides that amendments made to a party's case at an advanced stage of the proceedings (that is, after expiry of a period specified by the board in a communication under R. 100(2) EPC or after notification of a summons to oral proceedings) are generally to be disregarded unless there are exceptional circumstances which have been justified with cogent reasons by the party concerned. The case law on Art. 13(2) RPBA 2020 is reported in chapter V.A.4.5. "Third level of the convergence approach – submissions filed after notification of summons or after expiry of period specified in R. 100(2) EPC communication – Article 13(2) RPBA 2020".

The provisions mentioned above implement the "convergent approach", whereby the possibilities for parties to amend their case become increasingly limited as the appeal proceedings progress (see e.g. T 1370/15, T 2778/17 and the explanatory remarks in the preparatory document CA/3/19, section V.B.a), point 48, published in the supplementary publication 2, OJ 2020). Where their various individual requirements are met, the provisions are cumulatively applicable. See chapter V.A.4.1.2 "Primary object of appeal proceedings and the "convergent approach" to amendments made to party's case" below.

Parties must identify and justify any amendments to their case and state why they were not submitted at an earlier stage in the proceedings (Art. 12(4) and 13(1) RPBA 2020).