The wording of Art. 122(1) implies that re-establishment of rights is available only to applicants and proprietors. Therefore, opponents are in principle not entitled to request re-establishment of rights, e.g. in respect of the time limit for filing an appeal (see T 210/89). However, an opponent who has filed an appeal can request re-establishment of rights in respect of the time limit for submitting the grounds for appeal (see G 1/86).
Where re-establishment of rights is requested by the patent proprietor in respect of a time limit connected with the opposition procedure, the opponents are party to the re-establishment proceedings (see T 552/02 and T 1561/05).