Under R. 3(1) EPC (R. 1(1) EPC 1973) any party may use any EPO official language in written proceedings.

In T 706/91 the appeal had been drawn up in accordance with R. 1(1) EPC 1973 in one of the official languages, namely German. The appellant had therefore cited passages from the disputed European patent's claims and description in that language, even though they had been drawn up in French as the language of the proceedings. The board decided that these references were admissible.

In G 4/08 (OJ 2010, 572) the Enlarged Board of Appeal clarified that EPO departments cannot use, in written proceedings on a European patent application or an international application in the regional phase, an EPO official language other than the language of the proceedings used for the application under Art. 14(3) EPC (thereby overruling J 18/90, OJ 1992, 511).

R. 4(1) EPC (cf. R. 2(1) EPC 1973) allows any party to oral proceedings to use an official language of the EPO other than the language of the proceedings, provided he either gives the EPO at least one month's notice or arranges for interpreting into the language of the proceedings. Under R. 4(5) EPC the EPO must, if necessary, provide at its own expense interpretation into the language of the proceedings, or, where appropriate, into its other official languages, unless such interpretation is the responsibility of one of the parties.

In T 34/90 (OJ 1992, 454) the respondent did not give notice that he wished to use another official language in the oral proceedings and also failed to provide interpretation. His representative argued that because he had lawfully used an alternative official language in oral proceedings before the opposition division, he should be allowed to use the same language in the hearing before the board. The board reiterated the principle that appeal proceedings are not a mere continuation of first-instance proceedings, but are, for the purpose of deciding the permissibility of using an alternative official language under R. 2(1) EPC 1973 (R. 4(1) EPC), as for other procedural purposes, wholly separate and independent from those. Accordingly, the respondent's attempt to use the other language, without fulfilling the requirements of R. 2(1) EPC 1973 as they applied to the pending appeal proceedings, was rejected.

See also the communication from the Vice-President of DG 3, OJ SE 3/2007, 118.

In T 774/05 the board stated that R. 2(1) EPC 1973 (R. 4(1) EPC) implied that a party could choose to use one of the official languages set out in Art. 14(1) EPC 1973 and was entitled to speak and hear that language. However, a party had to be clear as to which official language it wished to use. The party then had a right to both speak and hear in that language, so long as the conditions of R. 2(1) EPC 1973 were fulfilled. The party did not, however, have a right to have a language in which it would speak and a different language in which it would listen.

In T 418/07 the respondent announced that it would use German at the oral proceedings (language of the proceedings being English) and requested the board to provide translation from German into English for the benefit of one of its employees who would attend the oral proceedings and who did not speak German. The board acknowledged the right of any party to use any of the three official languages in oral proceedings, but stated that the right to interpreting from either of the two other languages was circumscribed by R. 4 EPC. A party which elected to use a language which was not understood by one of its own representatives or employees could not for that reason request a free translation. The board could not provide translation merely to suit the convenience of a party.

In T 2422/10 the board rejected the respondent's argument that it had an absolute right to interpreting into English as the language of the proceedings. The general rule needed to be set against the principle of efficiency of the proceedings and the duty of all services of the EPO, including the boards of appeal, to observe the finances of the EPO. The wording of R. 4(5) EPC allowed the board to assess the necessity of such interpreting (cf. T 131/07). It was evident that the respondent's representative was quite capable of understanding any oral submissions of the appellant in German without interpretation.

The respondent was also accompanied by an expert, whom the board decided not to hear following the criteria of G 4/95 (OJ 1996, 412). In these circumstances the board considered that interpretation into English for the expert at the expense of the EPO would not be justified. Accompanying persons did not have an automatic right to it.

The matter of the language arrangements in oral proceedings in relation to an accompanying person also arose in T 131/07 and R 3/08 (for the latter see chapter V.B.4.3.18).

For a case which concerns the discretion given to the EPO under R. 4(1), last sentence, EPC to derogate from the provisions of this Rule, see T 982/08.

On the costs of interpreting in oral proceedings see also chapter III.C.8.2. and T 2109/15.