In order to maintain the quality of the audits, an ABC must have in place an audit control system. The role of the control is to ensure the constant quality of the audits, as well as to ease the handling of complaints.
The control is also a guarantee for advertisers and media agencies that the audit provides them with what they expect to get from it (they should not forget that they are not part of the audit process, but they are the users of the data, so careful non-publisher control is serving their best business interests).
The ABC has to have rules on how the auditors should maintain and archive their audit records, and it should design solutions for independent counter-audits.
The audit program is a guide for the audit controls. The audit inspectors (counter-auditors) should visit the audits, and review them on the basis of the audit program, then report to the ABC.
Sometimes problems may occur; therefore the ABC must be able to anticipate the problems, and in the case of their occurrence, it must be able to properly react to them.
Of course, as anything made by mad, the controls system is also subject to mistakes, and it has room for improvement.