The case law on "an isolated mistake in an otherwise satisfactory system" cannot be relied on to ignore a failure to act by the professional representative himself, unless there are special circumstances (T 1095/06).

In T 592/11 the board held that an isolated mistake by a professional representative in performing his check on the time limit once he has received the file to deal with was – as a rule at least – inexcusable (see also R 18/13 with reference to the travaux préparatoires).

In T 198/16 the representative did not notice that payment of the appeal fee had not been made. Different from an isolated mistake that an assistant may make, the board found that such a mistake was not excusable in a representative.

See also chapter III.E.5.5.4 e) "Ultimate responsibility of the representative".