Under R. 99(1)(a) EPC the notice of appeal shall contain the name and address of the appellant (see also R. 64(a) EPC 1973 according to which the notice of appeal is required to contain the name and address of the appellant in accordance with the provisions of R. 26(2)(c) EPC 1973. The relevant provisions are now R. 99 EPC and R. 41 EPC respectively).

In T 2330/10 the board stated that there was a difference between establishing the identity of an appellant and knowing the address where the appellant could be found. The deficiencies concerning the indication of the appellant's name and address as prescribed by R. 99(1)(a) EPC did not necessarily have to be remedied within the two-month time limit pursuant to Art. 108 EPC, but could be remedied later following an invitation under R. 101(2) EPC if there was a reason to issue such invitation. Whether or not the opponent knew the appellant's new address by the end of the two-month period was not relevant, nor was the degree of difficulty the opponent could have had in finding it out. The notice of appeal was therefore filed on behalf of a clearly identified legal person that was party to the first instance proceedings.

According to T 624/09 it has become standard case law that the provisions of R. 99(1)(a) EPC are satisfied if the notice of appeal contains sufficient information for identification of a party (see e.g. T 483/90, T 613/91 and T 867/91). In T 483/90 the appellant's name was incorrectly given and its address was missing but the number of the contested patent and the name and address of the professional representative were the same as those cited in previous proceedings. In T 613/91 the appellant's precise address was missing from the notice of appeal, but was known to the parties and the board from the opposition proceedings. In T 867/91 the notice of appeal did not contain the address of the appellant and did not expressly state that the patentee was the appellant. In T 624/09 the notice of appeal did not contain the appellant's address. In T 350/13 there was sufficient information available to identify the appealing party (opponent); the notice of appeal indicated the number of the European patent, the decision of the opposition division and the name of the patent proprietor. In both T 1636/13 and T 1712/10 it was possible to identify the appellant when the appeal was filed. It was alleged in T 899/95 that the opponent was a legal entity but was not identified by its official designation; its identity was, however, clear. In T 786/11, the board held that "IS Limited" did not change its legal identity by being transferred to Mauritius wurde (see also T 1458/12 and T 1201/14).

An appeal filed by an appellant whose name was changed before the appeal was filed without indicating the change of name met the requirements of R. 64(a) EPC 1973, provided that the appellant was identifiable (T 157/07). See also T 1/97, T 786/00 and T 866/01. According to T 866/01, the requirement regarding sufficient identification of the appellant was to be considered to be met whenever it is possible to establish beyond reasonable doubt the identity of the appellant on the basis of all information provided by the appellant or his legal representative within the time limit under Art. 108 EPC or in the previous proceedings, including any such information contained in the decision under appeal.

However, in T 938/94, where the appellant's name and address were not stated in the notice of appeal and it failed to give this information within the time limit set by the invitation pursuant to R. 65(2) EPC 1973, the appeal was rejected as inadmissible (see also T 774/05, in which the appeal was rejected as inadmissible, as the appellant's address was not given in the notice of appeal).

Several decisions have allowed correction of the name of the appellant to substitute a natural or legal person other than the one indicated in the appeal under R. 65(2) EPC 1973 in conjunction with R. 64(a) EPC 1973, if it was the true intention to file the appeal in the name of the said person and if it could be derived from the information in the appeal, if necessary with the help of other information on file, with a sufficient degree of probability that the appeal should have been filed in the name of that person (T 97/98, OJ 2002, 183; see also T 15/01, OJ 2006, 153, T 715/01, T 707/04 and T 875/06). Where there is objectively a deficiency in the notice of appeal indicating a genuine error as regards the identity of the appellant and there is objective evidence in the file indicating with a sufficient degree of probability who the appellant should be, then the notice of appeal may be corrected under R. 101(2) EPC (T 1961/09, following T 97/98, OJ 2002, 183) (see also T 540/09, T 662/09).

In T 445/08 date: 2012-01-30 (OJ 2012, 588) it was undisputed that the notice of appeal as filed was not admissible because the appellant company had not been a party to the opposition proceedings and accordingly was not adversely affected by the appealed decision. It was no longer the patent proprietor. The questions the board referred to the Enlarged Board included whether the request for correction, which would result in the appeal being admissible, was possible pursuant to R. 101(2) or 139 EPC. The request was filed only after expiry of the relevant two-month period provided for by R. 101(1) EPC.

In G 1/12 (OJ 2014, A114) the Enlarged Board of Appeal reformulated the question originally posed in T 445/08 date: 2012-01-30 (OJ 2012, 588) to ask whether, when a notice of appeal, in compliance with R. 99(1)(a) EPC, contains the name and the address of the appellant as provided in R. 41(2)(c) EPC and it is alleged that the identification is wrong due to an error, the true intention having been to file on behalf of the legal person which should have filed the appeal, it is possible to correct this error under R. 101(2) EPC by a request for substitution by the name of the true appellant.

The Enlarged Board answered that it was possible, provided the requirements of R. 101(1) EPC had been met. Given the explicit reference in R. 101(1) EPC to Art. 107 EPC and the possibility of remedying deficiencies only within the two-month appeal period under Art. 108, first sentence, EPC, the identity of the appellant, i.e. the person entitled to appeal, had to be established by expiry of the two-month period prescribed in Art. 108, first sentence, EPC at the latest. R. 101(2) EPC concerns deficiencies concerning the indication of the appellant's name and address as prescribed by R. 99(1)(a) EPC. They may be remedied irrespective of the time limits pursuant to Art. 108 EPC, upon invitation by the board of appeal (see also T 755/09).

The Enlarged Board fully endorsed the case law, in which it was considered that an incorrect indication of the appellant's identity is a deficiency which can be remedied, provided "its correction does not reflect a later change of mind as to whom the appellant should be, but on the contrary only expresses what was intended when filing the appeal" (see T 97/98).

The Enlarged Board also found that in cases of an error in the appellant's name, the general procedure for correcting errors under R. 139, first sentence, EPC was available under the conditions established by the case law of the boards of appeal. The following principles have been established:

(1) The correction must introduce what was originally intended. It is the party's actual rather than ostensible intention which must be considered.

(2) Where the original intention is not immediately apparent, the requester bears the burden of proof, which must be a heavy one (J 8/80).

(3) The error to be remedied may be an incorrect statement or an omission.

(4) The request for correction must be filed without delay.

In T 603/15 the board found that this last condition had not been met because four years had passed before the request for correction of an EPO Form 2300 under R. 139 EPC had been filed, and so it had to be refused in light of G 1/12.

An allowable correction under R. 139 EPC has retrospective effect (J 4/85 as endorsed in several subsequent decisions, for example J 2/92, OJ 1994, 375; J 27/96; J 6/02; J 23/03 and J 19/03).

Thus, an appeal filed by mistake in the name of an opponent who no longer exists but who has a universal successor, and which was obviously intended to be filed on behalf of the person who is the actual opponent and who was prejudiced by the decision, namely the universal successor, is admissible (T 1421/05).

In T 2561/11 the notice of appeal was only signed by the opponent’s representative without mentioning the opponent. The board was satisfied that a reader willing to understand would have understood, before the end of the time limit for filing an appeal, that the notice of appeal had been filed on behalf of the opponent. In T 2564/12, too, the true appellant was identifiable from the file, even if not correctly identified in the notice of appeal.

However, where the effective date of transfer of the patent to the appellant named in the notice of appeal had not actually occurred until after the period for filing a notice of appeal and it was the appellant's true intention to file an appeal on behalf of the name given in the notice of appeal, there is no deficiency in the notice concerning the name of the appellant which may be remedied in accordance with R. 99(1)(a) EPC in conjunction with R. 101(2) EPC nor an error which may be corrected pursuant to R. 139, first sentence, EPC and the appeal is thus inadmissible (T 128/10 following T 97/98; see also T 2045/09).

In T 979/12 the board noted that according to G 1/12, the board must establish the true intention of the appellant "on the basis of the information in the appeal or otherwise on file, i.e. ascertain who must be deemed in all likelihood to have filed the appeal...".

In T 445/08 of 26 March 2015 date: 2015-03-26 the board noted that it was not immediately clear that the appeal filed on behalf of the appellant, a company fully identified with its address and nationality and different from the patent proprietor, was actually intended to be filed on behalf of the appellant and stated that, regarding the requirements listed in G 1/12, it could not accept that the mere fact that the appellant was the party adversely affected during the opposition proceedings was sufficient to establish the true intention. The board stated that if it was indisputable that the notice of appeal was to be considered in the context of the file history, the true intention needed to be confirmed by external facts, at least to prevent requirements such as those of Art. 107 EPC being circumvented. It found that in applying R. 139 EPC to a party's request to correct a mistake in the notice of appeal in respect of the identity of the appellant, the principle of legal certainly, according to which parties are bound by their procedural acts, needed to be taken into consideration. The board concluded that the requirements for the correction requested had been met, and thus that the correction was to be allowed.