In J 3/93 the Legal 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, J 1/07, J 1/13).

In J 7/16 the Legal Board held that, in principle, negligence on the part of a professional representative would prevent a finding that all due care had been taken. However, in the case in hand the procedural behaviour of the former representative was not due to negligence, but to his state of health. For reasons beyond his control, the former representative had not been capable of running the case in a proper way although he had taken every effort to fulfil his duties. This finding prevented the applicant from suffering from the inappropriate procedural conduct of its former representative as it had no reason to suspect that he could not be relied on.

In T 381/93 of 12 August 1994 date: 1994-08-12 the board 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 Legal 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.

In T 2120/14 the board found the examining division's finding of lack of due care by the applicant to be justified in the circumstances, in which the observance of a time limit depended entirely on a single person who, in view of his impending extensive workload and travel, did not take the necessary precautions to ensure that the time limit could be met in case he was prevented from giving timely instructions. The board held that it was clear from the travaux préparatoires to Art. 122 EPC that the possibility of excusing the negligence of an employee who normally carries out his work in a satisfactory manner was not intended to be extended to the applicant or its professional representative (see R 18/13). In the case in hand it was an executive of the company who had failed to exercise all due care, who the board found was acting on behalf of the appellant.

In T 1954/13 the appellant (applicant) issued its US representative with an order to "stop work". It appeared to the board that the appellant could not expect that the "stop work" order would have no consequence at all, i.e. that work continued as usual. Yet, there was nothing on file which would suggest that measures had been taken by the appellant in order to somehow compensate for the issuance of the "stop work" order. If instructions had been given by the appellant to the effect that no information should be sent to it, the board found this would be an additional aspect for a finding that the appellant itself had not acted with all due care required by the circumstances.