We build a theoretical model to examine how supervision (auditing) can be utilized to enhance the efficiency of corporate governance and how collusive supervision (auditing) can be deterred. We introduce the outcomes of "Monotone Comparative Statics" ala Topkis (1978) and Edlin and Shannon (1998), and Milgrom and Segal (2002)\u27s generalized envelope theorem, and construct a three-tier agency model with a mathematically tractable structure. This should be an advantage in modeling in comparison with the collusion literature e.g., Kofman and Lawarree (1993)\u27s auditing application of the three-tier agency model ala Tirole (1986, 1992). The basic trade-off involved in adding the auditor (supervisor) into the hierarchy is the benefit from th...