Applicants can have their rights re-established only if they show that they were unable to observe a time limit vis-à-vis the EPO in spite of all due care required by the circumstances having been taken. The obligation to exercise due care must be considered in the light of the situation as it stood before the missed time limit expired. "All due care" means all reasonable care, i.e. the standard of care that the notional reasonably competent patentee, applicant or representative would employ in all the relevant circumstances (see T 30/90).[Art. 122(1); ]

For cases where the cause of non-compliance with a time limit involves some error in the carrying out of the party's intention to comply with the time limit, all due care is considered to have been taken if non-compliance with the time limit results either from exceptional circumstances or from an isolated mistake within a normally satisfactory monitoring system.

A finding of exceptional circumstances justifying the re-establishment of rights is dependent on the individual facts of the case. Examples include inter alia organisational upheavals and sudden serious illnesses. In such cases, the requesters must show not only the existence of those circumstances, but also that they took all due care, e.g. by carefully preparing the reorganisation or by having an effective staff substitution system.

Where an isolated mistake within a normally satisfactory monitoring system is alleged, the relevant party must show that the monitoring system normally works well. Such a system must include an independent, effective cross-check mechanism. However, this requirement does not apply to relatively small entities/patent departments (see T 166/87 and J 11/03).

The duty to exercise all due care applies first and foremost to the applicants and then, by virtue of delegation, to the representative duly entrusted by the applicant to act on their behalf in prosecuting the application (see J 3/93). The obligations of the applicant and those of their representative are clearly distinct and depend on the relationship between them (see T 112/89 and J 19/04). In this regard, the scope of the mandate and any express instructions given to the representative are taken into account.

Applicants are entitled to rely on their representative. To the extent that applicants are on notice that instructions are required in order to meet a time limit, they have however a duty to take all due care in the circumstances to meet the time limit (see T 381/93). The fact that the professional representative has acted correctly does not exempt applicants from suffering the consequences of their own mistakes or negligence.

European representatives are responsible in the procedure before the EPO and must be presumed to be supervising their own work continuously (see T 1095/06). When professional representatives have been instructed by their client to perform a particular procedural action and do not receive in due time the necessary additional instructions or required means, they must in principle take all necessary measures to try to obtain these instructions from their client and ascertain their true wishes (see T 112/89 and J 19/04).

Professional representatives can delegate routine tasks, such as typing, posting letters, noting time limits or checking due dates, to assistants. In those cases, the same strict standard of care is not expected of the assistant as is demanded of the representative himself. The representative must however show that the assistants have been carefully selected, duly instructed and periodically supervised (see J 5/80 and T 439/06).

If the applicants entrust a further party with taking care of their application matters, e.g. a non-European representative or a fee payment agency, it has to be established that such a party has taken the due care required of an applicant for or proprietor of a European patent (see J 3/88). In particular, a non-European representative must also show that a reliable system for the monitoring of time limits was in place when the time limit was missed (see J 4/07).