Under R. 76(2)(a) EPC and R. 41(2)(c) EPC, the notice of opposition must contain the name, address and nationality of the opponent and the state where his residence or principal place of business is located. R. 41(2)(c) EPC also gives precise particulars by which such identity needs to be established. If the identity of an opponent is not sufficiently established before expiry of the opposition period, the opposition is inadmissible (T 25/85, OJ 1986, 81). This defect cannot be remedied (T 590/94).
In T 870/92 the board emphasised that, when indicating a legal entity, failure to use its exact official designation (R. 26(2)(c) EPC and R. 61a EPC 1973; cf. R. 41(2)(c) and 86 EPC) did not necessarily mean that the opposition was inadmissible. An incorrect designation which nevertheless sufficed to indicate the party's identity had to be distinguished from the absence of such information. Errors in a designation could be corrected at any time (R. 88, first sentence, EPC 1973; cf. R. 139, first sentence, EPC; see also T 828/98).
In principle, the use of an abbreviation instead of the full name of a legal entity does not render an opposition inadmissible as long as the party's identity can be established. In T 1034/08, the board had no reasonable doubt that the abbreviation GSK stood for GlaxoSmithKline with regard to the identity of the Belgium-based opponent GSK Biologicals. Given that Belgian company law allows the co-existence of more than one company name and that GlaxoSmithKline Biologicals was the company's sole primary name, the board concluded that abbreviation GSK Biologicals did not constitute an incorrect designation of the opponent.
In T 1165/03 the board regarded an identity card or passport as the best evidence of identity but with the same proviso as applies to all evidence, i.e. that its value could be offset or even negated by other evidence. In this case, two different photocopy identity cards had been filed: the first had been sent to the opposition division and, although even less legible than the copy later faxed to the board, it was clearly not a copy of the same document as that shown in the fax and subsequently filed during the oral proceedings. The letter signed in the opponent's name said his name had only been used accidentally in relation to the proceedings and that he was more often at his work address than the home address shown on the identity card. However, there was no legible address on the earlier photocopy card on file. Moreover, the work address in the etter was not that shown on the second photocopy card filed with the board. The board therefore held that the identity card evidence was inherently unreliable and inconclusive.
Questioning the identity of an opponent is not enough to render the opposition inadmissible; cogent evidence must be put forward. In T 4/05 no such case was made. The appellant had not filed the extract from the commercial register which, it submitted during oral proceedings before the board, showed a different company name. This could therefore not be cited as evidence that the opponent's identity was unclear. The appellant's objection that two other companies were trading at the same address as the opponent also failed; this was merely an observation which could not affect the party status of an opponent who had been unambiguously identified.
In T 1426/13 the opposition had been filed on behalf of "Isarpatent GbR". The board noted that the lack of public registration of a GbR ("Gesellschaft bürgerlichen Rechts") could contribute to uncertainty or even confusion about the name and/or identity of a GbR at specific points in time. However, the EPO had to accept that such unregistered legal entities may be a party in proceedings before the EPO. Any relevant evidence had to be evaluated according to the principle of free and unfettered consideration of evidence (e.g. T 482/89, OJ 1992, 646). From the documents submitted the board was satisfied that a name change had occurred before the opposition was filed and that no other entity than Isarpatent GbR could have been the opponent. Nor was the admissibility of the opposition affected by any changes in the composition of the GbR after the opposition had been filed. A GbR may be held liable for its obligations, including costs which may be awarded to another party in EPO opposition proceedings. Therefore it was not necessary to determine the individual members (T 482/02 distinguished).
According to T 1551/10, for an opposition to be admissible, the opponent has to be identifiable by expiry of the opposition period (T 25/85, OJ 1986, 81), and provided this is the case, wrong information can be corrected (T 219/86, OJ 1988, 254; T 870/92). Extracts from the commercial register showed that Swisscom (Schweiz) AG was the (sole) universal successor in title to Swisscom Mobile AG, which was originally named as the opponent, although it had already been removed from the register before the opposition was filed. It was not apparent that any of Swisscom Mobile AG's business assets had been taken over by any other legal entity. Therefore, even though its predecessor in title had been wrongly named in the notice of opposition, Swisscom (Schweiz) AG was clearly and unambiguously identifiable as the opponent by the time the opposition period ended. Procedural statements mistakenly made in the name of a deceased party or of a legal person that no longer existed following a merger could be regarded as having been made in the name of their universal successor in title (T 15/01, OJ 2006, 153). The mistake in the opponent's name could therefore be corrected under R. 139 EPC. The public could not be misled because the register extracts showed only one successor in title at the time the opposition was filed, namely Swisscom (Schweiz) AG.
In T 1269/11 the board held that both R. 77 and R. 139 EPC were available in principle to rectify errors in the name of the respondent (opponent) as given in the notice of opposition (by analogy with G 1/12, OJ 2014, A114, concerning correction of the wrong identification of the appellant and summarised in Chapter IV.E.2.5.2 a)). However, there was not sufficient evidence to allow a correction in this case.
The availability of R. 139 EPC to correct the name of the opponent was confirmed by T 615/14 as follows. A request to correct the designation of the opponent in the notice of opposition is allowable under Rule 139, first sentence, EPC provided that it complies with the principles endorsed in G 1/12 (OJ 2014, A114), in particular that it reflects what was originally intended when filing the notice of opposition, that it does not give effect to a change of mind or development of plans and that it represents the opponent's actual rather than ostensible intention. The original intention at the time of filing the opposition can also be established on the basis of evidence submitted after the expiry of the opposition period.
Further deficiencies such as a wrong postal code or lack of signature may be subsumed under R. 76(2)(a) and R. 50(3) EPC, respectively, and can thus be remedied within a time limit set by the opposition division in accordance with R. 77(2) EPC. The opposition division can extend this time limit or set a new time limit if deemed appropriate (T 1632/06).