From an economic perspective, conventional fiduciary liability for self-dealing appears to raise little controversy. The accepted function of the duty of loyalty is to control opportunism in limited access arrangements. That legal duty is complemented by a variety of economic mechanisms that indirectly or incidentally perform the same function. Unfortunately, the conventional function is partially obscured by a number of conceptual confusions in the economic and legal literature. A review of the literature exposes the analytical misdirection and confirms the utility of the conventional proscription on self-interest.