In the course of the revision of the EPC, the time limit for intervention was transferred from Art. 105 EPC 1973 to R. 89(1) EPC, which states that notice of intervention shall be filed within three months of the date on which proceedings referred to in Art. 105 EPC are instituted. The word 'court' has been deleted entirely, since an action for declaration of non-infringement does not have to be instituted before a court in all states.
In T 452/05, the board considered three dates which could possibly have triggered the three month period: the date on which the request for an interim injunction was made, the date on which the request was granted, or the date when the injunction order was served upon the opponent. In the board's view, only the last date should be regarded as the decisive point in time, as only from that date onwards could the opponent provide evidence of the proceedings that entitled it to intervene. The applicable starting point for calculating the threemonth period for intervention was always the date of the institution of the first court action, when the sole available period for intervention started to run. The two alternative starting points under Art. 105(1) EPC 1973 for calculating the three-month period for intervention were mutually exclusive (T 296/93, OJ 1995, 627). See also T 144/95. Art. 105 EPC 1973 could not be used to give an opponent who failed to file an appeal in time a second chance, as the opponent does not fulfil the requirement of being a third party (T 1038/00).