1.5. Time limit for intervention

Under R. 89 EPC, intervention is not possible until the opposition period has expired (this was previously laid down in Art. 105 EPC 1973), but notice of it must be filed within three months of the date on which proceedings referred to in Art. 105 EPC were instituted.

If multiple proceedings are under way, the three-month time limit for intervening is always triggered by the date on which the first proceedings were instituted (T 296/93, T 1143/00).

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 and T 18/98. 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).

In T 694/01 the board held that Art. 105(1) EPC 1973 did not stipulate when infringement proceedings were deemed to have been instituted. As they could only be instituted before the national courts, the wording of Art. 105 EPC, even if not explicitly, set this date by reference to the relevant national procedural laws.

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.

In T 691/16 the appellant (patent proprietor) disputed that the three-month time limit prescribed by Art. 105 EPC and R. 89 EPC had been adhered to since the date on the advice of delivery recording service of the notice of action was not clearly legible and, moreover, the signature on it was allegedly not identical to the intervener's. The board ruled that the intervention had been filed properly and in due time. Proving service was the very point of the advice of delivery, and both the stamped date and the handwritten date (in so far as it was legible) showed the relevant date. So there was at least prima facie evidence against which the patent proprietor had not asserted any substantiated doubts. Moreover, R. 126(2) EPC, last half of the sentence, EPC reflected a general principle whereby, in case of doubt, it was for the sender of a document, not the recipient, to prove that it had reached the recipient and when. Doubts owing to things such as illegibility therefore could not act to the recipient's detriment. As regards the differences in the signature, the board pointed out that a notice of action did not necessarily have to be served on the recipient itself, but could also be served on people living in the building or with the necessary authorisation. This was generally what happened at companies. There was therefore no reasonable doubt that the intervener's claim to have received the notice of action on the relevant date was true.