In J 3/93 the board ruled that the duty to exercise all due care stipulated by Art. 122 EPC 1973 applied first and foremost to the applicant and then, by virtue of the delegation implicit in his appointment, to the professional representative authorised to represent the applicant before the EPO. The fact that the representative had acted correctly did not exempt his client from suffering the consequences of his own mistakes, or even negligence (see also J 16/93, J 17/03).
In T 381/93 the board of appeal observed that the applicant was entitled to rely on his duly authorised professional representative to deal with the EPO. However, the board held that to the extent that he was on notice that a time limit had not been met and/or that instructions were required in order to meet it, an applicant had a duty to take all due care in the circumstances to meet the time limit.
In J 22/92 the board held that the applicant, who had appointed US attorneys for the purpose of the PCT application, was entitled to believe that a copy of a communication had been sent to the US attorneys as well. The board referred to the principle of proportionality and stated that the loss of the patent application as a result of what may be considered at most a minor procedural irregularity would otherwise appear an extremely severe result. The board held that, in the case in point, the due care to be considered was in fact not that which was expected from a professional representative but that which was expected from an applicant unaware of the proceedings.