In J 9/86 the Legal Board was of the opinion that in a large firm where a large number of dates had to be monitored at any given time, it was normally to be expected that at least one effective cross-check was built into the system (T 223/88, J 26/92, T 808/03 of 12 February 2004 date: 2004-02-12, T 1149/11).

In T 828/94 the board held that given the size of the representative's office, a proper monitoring system should have contained some form of cross-check, for example that someone would be responsible for checking independently of the representative and the assistant whether any notice of appeal had been filed or was being prepared, and for raising the alarm if no data concerning such a notice – or a decision not to appeal – had been entered into the computer near the due date. In T 257/07 the board emphasised that an independent cross-check must necessarily include either another person or an automated system alerting another person (see also J 9/16).

In T 686/97 of 12 May 1998 date: 1998-05-12 the board held that the provision of a "redundant" or "failsafe system" was an essential component of a normally satisfactory reminder system in corporate patent departments. The failure to provide administrative reminders to the responsible patent attorneys of the time limits applying to the filing of statements of grounds of appeal was incompatible with the operation of a normally satisfactory system.

In T 428/98 (OJ 2001, 494) the board stressed the exceptional nature of the ruling in J 31/90 and T 166/87 of 16 May 1988 date: 1988-05-16 (which concerned cross check mechanisms in small offices; see chapter III.E.5.4.4 b) below) and said that according to the appellant's submission his representatives' office was staffed by two patent agents, two lawyers, a partly qualified patent lawyer ("Patentassessor") and a law graduate, i.e. six people dealing in their main professional capacity with cases relating to intellectual property rights. Such cases being commonly subject to time limits, with immediate negative legal consequences for the client if they were missed, time-limit monitoring in such an office was a major undertaking in terms of both significance and scale. The board therefore deemed a cross-checking mechanism to be essential. See also T 1962/08, T 1726/08 (a firm with 40 attorneys at four locations is not small), T 479/10.

In T 283/01 of 3 September 2002 date: 2002-09-03 the board pointed out that the applicant's system was not properly designed to handle the appeal in question, involving partial responsibility of an external representative. The deviation from the normal way of filing and prosecuting an appeal had been the applicant's deliberate decision in the particular circumstances of the case. Taking all due care required by the circumstances of the case should have implied installing an individual control mechanism, offering a realistic possibility of detecting and correcting the failure to note and calculate the time limit for filing the statement of grounds.

T 261/07 concerned a case in which an intermediary delivery service received and distributed mail within the patentee's premises. The board held that there had been no effective cross-check. Such a failsafe system would have required a regular comparison between the mail room database and the database of the Central Intellectual Property Department in order to discover discrepancies.

In T 1962/08 the representative argued before the board that an independent cross-check in the system for monitoring time limits was not obligatory. The board confirmed what had been said in T 428/98, namely that the requirements to be met by a system for monitoring time limits in general included making sure that monitoring duties were not left to one person alone, but that the system incorporated an overall checking mechanism which was independent of the person responsible for monitoring time limits. This checking mechanism could be provided within a single system for monitoring time limits. If the checking mechanism involved a second system for monitoring time limits, the latter had to be independent of the former ("redundant"). See also T 1465/07 in which the board held that the additional burden of an independent cross-check was not disproportionate for a large firm, where the cross-check can be organised more economically than in a smaller one. In T 1149/11 the board held that the duty of care concerning supervision of the assistant required that an effective cross-check was implemented, at least in a firm where a large number of time limits have to be monitored.

In T 836/09 of 17 February 2010 date: 2010-02-17 there was an isolated mistake by an assistant within an otherwise satisfactory system of processing outbound mail. The board held that in such a situation, irrespective of whether or not a large firm was concerned, the duty of having at least one effective cross check built into such a system was dispensed with. This applied even to important letters such as those whose improper treatment may entail the loss of a right or means of redress. The reason was that, in contrast to the monitoring of time limits, the risk of an error in the processing of outbound mail was low because such processing generally involved the execution of straightforward steps (with reference to T 178/07; see also T 1171/13 and T 2023/14 in relation to the sending of a fax by an assistant).

Concerning the need for an independent cross-checking mechanism and the form it should take, see also T 1172/00, T 785/01 of 30 September 2003 date: 2003-09-30, T 36/97, T 622/01, J 1/07, J 13/07.