Rule 151¹⁵⁸
Appointment of a common representative

(1) If there is more than one applicant and the request for grant of a European patent does not name a common representative, the applicant first named in the request shall be deemed to be the common representative. However, if one of the applicants is obliged to appoint a professional representative, this representative shall be deemed to be the common representative, unless the applicant first named has appointed a professional representative. The same shall apply to third parties acting in common in filing a notice of opposition or intervention and to joint proprietors of a European patent. 

(2) If the European patent application is transferred to more than one person, and such persons have not appointed a common representative, paragraph 1 shall apply mutatis mutandis. If such application is not possible, the European Patent Office shall invite such persons to appoint a common representative within a period to be specified. If this invitation is not complied with, the European Patent Office shall appoint the common representative.