The United States Constitution established a union of states that provided for national and state government and gave each its own authority and sphere of power. However, it also allows for these spheres to overlap and thus creates areas of concurrent power in which either level of government or both may regulate. Examples include the power to regulate commerce and the power to tax. Within these areas there may be situations in which laws conflict. To resolve these conflicts, the Constitution’s Supremacy Clause provides that federal law is “the Supreme Law of the Land,” thereby preempting state law. Preemption occurs when the Congress enacts a statute or a federal agency adopts a regulation in an area in which state legislatures have acted or have the authority to act. The Congress’s constitutional power to regulate interstate commerce has proven the source of many preemptive statutes. The balance between federal and state government in areas of concurrent powers has been continuously debated and has shifted as political, social, and economic conditions have changed over the years. Within the 20th century, for example: The Great Depression of the 1930s led to an expanded federal role in domestic affairs to deal with social and economic problems that states could not respond to effectively on their own. The Great Society programs of the 1960s brought further expansion of the federal role in an effort to achieve socially desirable outcomes and to the use of state and local governments as intermediaries to implement national policies in areas that had previously been the purview of state or local governments or the private sector. The 1980s brought a shift of funds, authority, and responsibility to the states through block grants, such as the Social Services Block Grant, which allowed greater state and local autonomy and flexibility in fashioning local strategies to address federal objectives. The trend toward state flexibility continued in the 1990s, accompanied by concern about “unfunded mandates” (federal regulations that impose new duties on states—duties that require state expenditures). At the same time, the emergence of the Internet and the increasingly national and international nature of commerce created pressures for federal regulation. Questions of federal and state responsibility in areas of common regulatory concern continue to spark debate in the twenty-first century, as evidenced by the examination of state-regulated voting procedures following the 2000 presidential election and of federal and state homeland security responsibilities following the terrorist attacks of 2001. Such questions are also likely to arise during reauthorization debates on existing programs. To identify mechanisms for focusing state efforts toward national regulatory objectives, we reviewed the literature on federalism, intergovernmental relations, preemption, and regulatory programs in a broad range of policy areas. We then examined programs and approaches that combined federal with state regulation or implementation. Our review included both programs that involved preemption and programs that used other approaches to enlist state effort in support of federal or national regulatory objectives. Five major mechanisms emerged from our review. We classified programs in terms of these mechanisms and selected two or more programs representing each mechanism for more detailed examination and to serve as examples. We selected examples from a broad range of regulatory agencies with the aim of including major programs as well as a variety of approaches. (The programs we selected are summarized in table 1). For the mechanism concerning grants, we looked at grant programs but did not examine other forms of federal support. Our study focused on the mechanisms and did not review the content or strategic approaches of the regulations and standards involved or the effectiveness of the programs as implemented. To obtain descriptive material concerning each of these programs we reviewed authorizing statutes, regulations, agency documents, and documents concerning quasi-official standard-setting bodies. We also examined reports from program studies conducted by the Congressional Research Service, GAO, inspectors general, and other sources. We did not conduct new analyses of these programs. Thus, our findings are based on available information. It should be noted that each of the mechanisms we describe represents an ideal type—that is, the elements listed for each mechanism are characteristic of that mechanism and define a “pure case” to which specific programs can be compared. In the real world, few, if any, programs will match the “pure case” completely, and a complex program may incorporate more than one mechanism. We conducted our work between June 2001 and February 2002 in accordance with generally accepted government accounting standards. Because our work drew only on already available materials, we did not seek agency comments on our findings. We identified five regulatory or standard-setting mechanisms and four patterns of implementation or enforcement that characterize areas in which the federal government and the states share regulatory objectives and responsibilities. The five mechanisms are: fixed federal standards that preempt all state regulatory action in the subject area covered; federal minimum standards that preempt less stringent state laws but permit states to establish standards more stringent than the federal; inclusion of federal regulatory provisions in grants or other forms of assistance; cooperative programs in which voluntary national standards are formulated by federal and state officials working together; and widespread state adoption of voluntary standards formulated by quasi- official entities. The first two mechanisms involve preemption. The other three represent alternative approaches. The mechanisms differ in terms of which level of government sets standards and whether application of the standards within a state is voluntary or mandatory. The mechanisms also offer different options with respect to implementation or enforcement. Fixed federal standards and minimum federal standards permit three patterns of implementation: (1) direct implementation by the federal agency, (2) implementation by the states, approved by and under some degree of oversight by the federal agency, and (3) a combination of federal agency and federally approved state implementation. Grants follow the second of these patterns. The remaining two mechanisms follow a fourth pattern, direct implementation by the state under its own authority. These three mechanisms vary in the degree of federal oversight they can accommodate. Standard-setting mechanisms and implementation options in the programs we reviewed form combinations as illustrated in table 2. We will discuss each mechanism, implementation options associated with that mechanism, and operational issues that have arisen in the programs we reviewed. The federal government sometimes assumes sole regulatory authority over a specified subject area, either by prohibiting states from regulating or by issuing federal regulations that states must follow. Both statutes and treaties can preempt in this way. When federal statutes indicate that Congress intended the federal government to assume sole regulatory authority over a specific subject area, states cannot establish either stricter standards or standards that are less strict than the federal. A program under federal regulatory authority may involve (1) no state role, (2) a parallel state regulatory and implementation role, or (3) state implementation of the federal regulatory provisions or standards. In some instances, the federal government both regulates and assumes responsibility for enforcement or implementation—states do not perform either function. In addition to establishing uniform standards nationwide, this approach establishes a single locus of accountability and program direction. The federal agency that administers the program provides the resources and bears the costs. Regulation of employer-based pension plans, pursuant to the Employee Retirement Income Security Act of 1974 (ERISA), provides an example. Federal standards were viewed as needed in light of the importance of these plans to interstate commerce and the need to protect employees and their beneficiaries from loss of benefits due to unsound or unstable plans. ERISA established, among other requirements, fiduciary, reporting, and disclosure requirements that apply to private employee pension plans in the United States. ERISA supersedes all state laws that relate to ERISA pension plans. The Pension and Welfare Benefits Administration (PWBA) of the Department of Labor is responsible for administering and enforcing these ERISA provisions, and states do not have an enforcement role. In other instances, regulatory authority is divided between the federal government and the states. States retain the power to establish and implement regulations for their portion of the sector but are precluded from applying them within the federal portion. Regulation of health coverage under ERISA provides an example. The federal government regulates all employee health plans. If an employer chooses to provide coverage through an insurance policy, that policy is subject to state regulations. Approximately 60 percent of individuals participating in employer sponsored plans are covered by state regulated insurance policies. This division of authority can lead to potential differences in coverage requirements, uncertainty, and litigation. As a result, individuals in similar plans may have different rights and remedies. Federal legislation in certain health coverage standards in recent years has set federal minimum standards that generally apply to all health plans. In some program areas, states implement or enforce federal standards that preempt state laws or regulations. The Hazardous Materials Transportation Act, as it applies to motor vehicles, illustrates this approach. In order to provide adequate nationwide protection against the risks to life and property inherent in the transportation of hazardous materials, this act authorizes the Secretary of Transportation to regulate the transportation of such hazardous materials not only in interstate and foreign commerce but also in intrastate commerce. The act and federal regulations prescribed under the act generally preempt state requirements that are not substantively the same as the federal. However, most of the roadside commercial vehicle inspections applying hazardous material (HAZMAT) regulations are done through state programs. Under the Motor Carrier Safety Assistance Program (MCSAP), states that meet grant requirements can take responsibility for enforcing these regulations for both intrastate and interstate vehicles, and nearly all states have done so.These requirements include adopting state HAZMAT transportation regulations identical to the federal regulations for commercial vehicles and having the legal authority and resources to enforce them. In return, the states receive federal grants to cover a portion of their program costs. Enlisting the efforts of state agencies greatly expands the resources available for implementation or enforcement. In each of the programs we examined, activities to support federal regulations built upon activities that states already performed. However, this strategy also raises some major operational issues or questions, for example: Who will carry out enforcement activities in states that are unwilling or unable to do so? What share of state program operation costs, if any, should the federal government cover? Which level of government is accountable for ensuring that state performance is adequate, and for taking action if it is not? Is uniformity of enforcement important, and if so how can it be achieved? State implementation was an option under each of the five standard- setting mechanisms we examined.