The exercise of dual federal-state and/or multiple discipline regulatory agency jurisdiction over the same or related activity affords a fruitful source for constitutional challenge as to the authority of one or more of the regulators. Consequently, the allocation of authority (whether dual, exclusive, or superior/subordinate) over a challenged activity often is resolved by the courts whose decisions may ultimately be altered by legislative action. To understand the current and likely future dual federal-state regulation of the insurance business, a general grasp of the constitutional principles governing the allocation of regulatory power is essential. In the context of insurance regulation, this involves the constitutional issues relating to (a) the applicability of the preemption doctrine, (b) the limitations posed by the Commerce Clause and (c) the impact of the McCarran Act.