T 0936/09 of 01.03.2012

Under the EPC, there is no legal obligation for the patent proprietor to take an active part in opposition proceedings. However, the patent proprietor is not free to present or complete his case at any time that he wishes during the opposition or opposition appeal proceedings, depending, for example, on his procedural strategy or his financial situation. In view of the judicial nature and purpose of inter partes appeal proceedings (see point 2 of the Reasons) and in the interests of an efficient and fair procedure, the board considers it necessary that all parties to opposition proceedings complete their submissions during the first-instance proceedings in so far as this is possible. If a patent proprietor chooses not to respond in substance at all to the opposition, for example by filing arguments or amended claims, or chooses not to complete his submissions at the stage of the first-instance proceedings, but rather presents or completes his case only in the notice of appeal or the statement setting out the grounds of appeal, then he will need to face the prospect of being held to account for such conduct by the board when, for example, exercising its discretion under Article 12(4) RPBA. (See point 9 of the Reasons). This applies in particular if, as in the present case, all the reasons for revocation of the opposed patent were known to the patent proprietor before it received the impugned decision (see point 10 of the Reasons).