In J 15/92 the Legal Board of Appeal held that in the case of a request whose true nature was uncertain (here it was unclear whether it was a request for re-establishment or a request for a decision), the EPO should clarify the matter by asking the requester. It would have been sufficient in the case in point for the EPO to invite the applicant to define his request more precisely. For the EPO to interpret the request arbitrarily constituted an error rendering the impugned decision null and void (see also J 25/92 and J 17/04).
In J 6/08 the board added that a request (for a decision or re-establishment) filed with a view to obtaining the redressal of a loss of rights within the meaning of R. 69(1) EPC 1973 had to be interpreted by the EPO in the light of the requester's objectively discernible will and taking account of the particular circumstances of the case. In case of doubt the Office is obliged to establish what the requester really wanted and may also be obliged to point out any still outstanding procedural steps in connection with this request (in this case, observance of the period of one year under Art. 122(2) EPC 1973).
Though not expressly relying on the principle of legitimate expectation, the Enlarged Board of Appeal held in R 14/10 that in cases where a request of a party during oral proceedings was considered unclear, it was the duty of the deciding body to ask for clarification before deliberation. However, if the requests as read out before the debate was declared closed did not correspond to the petitioner's intention, it was the petitioner's duty to intervene at that point.