In T 438/87 the question addressed was whether a delay in publication of the European patent specification could affect the calculation of the nine-month period for filing an opposition. The board concluded that, since the mention of the grant of the patent in suit had been brought to the public's attention in the normal way, it was from this date that the opposition period had begun, irrespective of what problems may have affected publication of the patent specification and what consequences such untoward event might have for certain third parties owing to their geographical location.

According to T 1644/10, the opposition period is triggered solely by the grant of a European patent and publication of the mention of its grant in the European Patent Bulletin. The mention in the European Patent Bulletin that a correction of the patent specification has been issued does not trigger either a first or any "further" opposition period, even if the corrected specification confers a broader scope of protection than that conferred by the one originally published.

In T 2061/12, the board noted that the EPO distinguished between fax parts received before and after midnight, according them different filing dates (T 683/06, T 2133/10; decision of the President dated 12 July 2007, OJ SE 3/2007, 7). In this case, only the last page and possibly part of the penultimate one had arrived after midnight, while Form 2300 signed by the patent agent, the payment form and at least the first two pages of the notice of opposition – which at a minimum substantiated a novelty objection – had all certainly reached the EPO before midnight. The opposition had therefore been filed in due time under Art. 99(1) EPC; it also complied with R. 76(1) and (2) EPC. It was therefore admissible (R. 77(1) and (2) EPC).