Both executive management and the board should be engaged enough in the process to determine if these reviews are in fact independent of the operating areas they are designed to review, and that the senior officers in those roles can speak freely on issues that need to be addressed.
Audit committee members should have regular time in meetings to talk with the outside auditors without managers present. Best practices for audit committee processes have been laid out many times, including in the 1980s by the Treadway Commission and in 2000 by the Blue Ribbon Committee. Beyond that, boards of directors and managers should periodically test where they stand on ethical business practices.