policy in this area must be directed toward prevention, early detection and treatment, and research. P Legal constraints . Domestic laws and international agreements place limits on property rights, the right of eminent domain, due process, constitutional limits on a particular agency = s activities, and so on. These legal constraints often play an important role in shaping the realm of public policy. P Administrative constraints . Effective programs require competent management and execution. Qualified individuals must be available to carry out social objectives. Even the best-conceived program is doomed to failure unless managers and workers with the proper mix of technical and administrative skill are available. P Distributional constraints . Social programs and public-sector investment projects affect different groups in different ways. The A gainers @ are seldom the same as A losers. @ When distributional impacts of public policy are of paramount concern, the objective of benefit-cost analysis might maximize subject to the constraint that equity considerations be met. P Political constraints . That which is optimal may not be feasible because of slowness and inefficiency in the political process. Often what is best is tempered by what is possible, given the existence of strong competing special-interest groups. P Budget constraints . Public agencies often work within the bounds of a predetermined budget. As a result, virtually all social programs and public-sector investment projects have some absolute financial ceiling above which the program cannot be expanded, irrespective of social benefits.