If the European Patent Office issues a promise or statement on how to act in a given area, the principle of legitimate expectations requires that promise or statement to be honoured unless there is good reason not to do so. Users and representatives cannot be expected to question, without any apparent reason, statements on the extension of time limits which are made in publications under Rule 134(4) EPC. Even in the absence of a general dislocation in the delivery or transmission of mail, they can rely on such publications without suffering any disadvantages (points 1.12.-1.20 of the Reasons).

The established approach of applying the due-care criterion to the question of removal of the cause of noncompliance under Rule 136 EPC leads to an additional admissibility requirement, by expanding the scope of the substantive due-care criterion, which has no basis in the EPC. Removal of the cause of non-compliance is a question of fact which occurs on the date on which the person responsible for the application or patent actually became aware of an error (actual knowledge), rather than when this person ought to have noticed the error (presumption of knowledge). Pursuant to Article 122(1) EPC, if failure to observe a time limit is due to an error of fact, the due-care criterion is to be assessed only in the context of the merits of a request for re-establishment of rights. The same applies if failure to observe a time limit is based on an error of law. Thus, the due-care criterion is to be assessed only in the context of the merits of the request and removal of the cause of non-compliance occurs when the responsible person actually became aware of the error of law.

Dans l'affaire T 198/16, la chambre a indiqué que la pratique actuelle consistant à appliquer l'exigence de vigilance dans le contexte de la cessation de l'empêchement au sens de la règle 136(1) CBE pouvait être considérée comme étendant la signification de l'exigence de vigilance d'une manière qui élargit la portée de ce critère essentiellement de fond en y ajoutant la fonction d'obstacle préliminaire extraordinaire à la recevabilité/à l'applicabilité. La chambre a indiqué que cette approche concernant le critère de "cessation", qui ne pouvait pas être fondée sur la lettre des dispositions, était par conséquent douteuse. La chambre a laissé ouverte la question de l'approche à suivre.