In T 1081/02, the board held that the communication issued by the opposition division's formalities officer during the period for appeal, stating that the decision already issued had been sent by mistake and should therefore be disregarded, could not constitute a legally sound basis for regarding the decision's validity as so doubtful that it could be considered void. According to the applicable principle of the protection of legitimate expectations, however, the parties could not be deemed to have failed to comply with the time limit for filing a notice of appeal (Art. 108 EPC 1973) (see also T 466/03).
In T 830/03 the opposition division had issued a second written decision together with a communication which suggested that the first written decision was superseded. The opponent filed a notice of appeal outside the period of four months after the date of the notification of the first decision, but within the time limit after the notification of the second decision. The board held that the only legally valid written decision was the first decision but that, in application of the principle of protection of legitimate expectations, the appeal was deemed to have been filed in time.
In T 124/93 the opposition division, after having delivered its decision, re-delivered the same with an additional enclosure under a new mailing date. This had misled the parties about the time limit for filing the notice of appeal and statement of grounds. Applying the principle of the protection of legitimate expectations, the board ruled that the appeal was to be considered as filed in due time (see also T 972/05, for another example of re-dating the decision).