In J 35/92 the first-named of two individual joint applicants had transferred his rights in the application to a company, which had appointed another representative who had then purportedly withdrawn the application. The second applicant did not agree with the withdrawal. The department of first instance held that the company was entitled unilaterally to withdraw the application by virtue of R. 100(1) EPC 1973, according to which the first-named applicant could be regarded as the representative of both, but the board of appeal disagreed. R. 100 EPC 1973 applied only where no joint professional representative had been appointed, whereas in the case in question the original applicants had appointed a representative, who continued to act for the second applicant. The board therefore concluded that the purported withdrawal of the application by the first-named applicant was invalid. The parties were given two months to appoint a joint professional representative, failing which one would be appointed by the EPO.
In J 10/96 the Legal Board of Appeal ruled that where several applicants were represented jointly by a professional representative, who during the course of proceedings ceased to represent his clients, the correct procedure to be followed was that contained in R. 100(2), second sentence, EPC 1973, according to which the applicants were to be requested by the EPO to appoint a common representative within two months. If this request was not complied with, the EPO was empowered to appoint the common representative.
In G 3/99 (OJ 2002, 347) the Enlarged Board of Appeal dealt with the question of the admissibility of joint oppositions and joint appeals. The decision makes it clear that an opposition filed in common, apart from the fact that it is filed by more than one person, is as much a single opposition as an opposition filed by only one person. Consequently, the common opponents are obliged to act in common through their duly determined common representative. In an opposition filed in common, there must in all cases be a common representative (Art. 133(4) and R. 100 EPC 1973), and only that common representative is entitled to act in the opposition proceedings on behalf of all the common opponents taken as a whole.
The decision further notes that an individual common opponent not being the common representative, or a subgroup of the group who filed the opposition in common, but without their common representative, is not allowed to act or intervene on his own or on behalf of one or more or all of the other individuals. Thus, only the common representative is entitled to sign the filed documents (R. 100 and R. 36(3) EPC 1973), the signature of other individuals not being required. At any stage of the procedure, be it the opposition or the appeal procedure, it may also occur that the joint member who is the common representative intends to withdraw from being a joint member, i.e. to withdraw from the proceedings. In such circumstances, he must notify his decision to the EPO with the procedural consequence that, for the determination of a new common representative, the provisions of R. 100(1) EPC 1973 have to be applied for the opposition procedure by virtue of the last sentence of that rule and, for the subsequent appeal procedure, by virtue of R. 66(1) EPC 1973.
It may also occur that the common representative ceases to act in the procedure without the EPO being informed thereof. In both cases, the other joint members must take the appropriate action to continue the procedure in due time and to inform the EPO of the new common representative, if appointed. However, there is no practical need to acknowledge the validity of procedural acts of a joint member who is not the common representative. Since a procedural act performed by a non-entitled person is treated by the EPO in the same way as a missing signature (see T 665/89), each joint member or any other person acting on his behalf can perform such an act to avoid missing a time limit, provided the deficiency is remedied within a further time limit set by the board in the communication under R. 36(3) EPC 1973 notified to the common representative and sent for information to the non-entitled person who performed the act. The deficiency can be remedied if the procedural act is signed by the common representative. If, for whatever reason, this person ceases to be a joint member, the signature must be provided by a new common representative appointed pursuant to R. 100 EPC 1973.
G 3/99 was applied in T 1154/06 in connection with the necessity of appointing a professional representative if the first-named of multiple patent proprietors was not resident in a contracting state. (See R 18/09, in which the Enlarged Board referred to these two decisions and held that both the principle that a plurality of persons acting in common must be treated as a single party (a "group party") and the requirement that such a group party acts through a common representative apply to petition proceedings.)
Decision T 418/07 concerns a different case, where shortly before the oral proceedings the respondent/patent proprietor appointed a second firm of representatives as joint representatives in addition to the firm already acting and asked the board to send copies of all correspondence to both firms. In this case of multiple representatives, the board held that while it is open to a party to appoint as many representatives as it may wish, the board is not aware of any requirement on it or on other parties to send correspondence to more than one representative of one party. If a party wants to retain multiple representatives, it must make its own arrangements for copying correspondence to them all. Parties cannot expect the board to provide copying services for their convenience.
The issue of the validity of an appeal filed by a person who is not the common representative named under R. 151 EPC (R. 100 EPC 1973) in the notice of opposition is dealt with in the Chapter "Appeal procedure".