When Congress does use its power under the commerce clause, it can expressly state that it wishes to have exclusive regulatory authority. For example, when Congress determined in the 1950s to promote nuclear power (“atoms for peace”), it set up the Nuclear Regulatory Commission and provided a limitation of liability for nuclear power plants in case of a nuclear accident. The states were expressly told to stay out of the business of regulating nuclear power or the movement of nuclear materials. Thus Rochester, Minnesota, or Berkeley, California, could declare itself a nuclear-free zone, but the federal government would have preempted such legislation. If Michigan wished to set safety standards at Detroit Edison’s Fermi II nuclear reactor that were more stringent than the federal Nuclear Regulatory Commission’s standards, Michigan’s standards would be preempted and thus be void.

Even where Congress does not expressly preempt state action, such action may be impliedly pre-empted. States cannot constitutionally pass laws that interfere with the accomplishment of the purposes of the federal law. Suppose, for example, that Congress passes a comprehensive law that sets standards for foreign vessels to enter the navigable waters and ports of the United States. If a state creates a law that sets standards that conflict with the federal law or sets standards so burdensome that they interfere with federal law, the doctrine of preemption will (in accordance with the supremacy clause) void the state law or whatever parts of it are inconsistent with federal law.

But Congress can allow what might appear to be inconsistencies; the existence of federal statutory standards does not always mean that local and state standards cannot be more stringent. If California wants cleaner air or water than other states, it can set stricter standards—nothing in the Clean Water Act or Clean Air Act forbids the state from setting stricter pollution standards. As the auto industry well knows, California has set stricter standards for auto emissions. Since the 1980s, most automakers have made both a federal car and a California car, because federal Clean Air Act emissions restrictions do not preempt more rigorous state standards.

Large industries and companies actually prefer regulation at the national level. It is easier for a large company or industry association to lobby in Washington, DC, than to lobby in fifty different states. Accordingly, industry often asks Congress to put preemptive language into its statutes. The tobacco industry is a case in point.

The cigarette warning legislation of the 1960s (where the federal government required warning labels on cigarette packages) effectively preempted state negligence claims based on failure to warn. When the family of a lifetime smoker who had died sued in New Jersey court, one cause of action was the company’s failure to warn of the dangers of its product. The Supreme Court reversed the jury’s award based on the federal preemption of failure to warn claims under state law.Cippolone v. Liggett Group, 505 US 504 (1993).

The preemption doctrine derives from the supremacy clause of the Constitution, which states that the “Constitution and the Laws of the United States…shall be the supreme Law of the Land…any Thing in the Constitutions or Laws of any State to the Contrary notwithstanding.” This means of course, that any federal law—even a regulation of a federal agency—would control over any conflicting state law.

Preemption can be either express or implied. When Congress chooses to expressly preempt state law, the only question for courts becomes determining whether the challenged state law is one that the federal law is intended to preempt. Implied preemption presents more difficult issues. The court has to look beyond the express language of federal statutes to determine whether Congress has “occupied the field” in which the state is attempting to regulate, or whether a state law directly conflicts with federal law, or whether enforcement of the state law might frustrate federal purposes.

Federal “occupation of the field” occurs, according to the court in Pennsylvania v. Nelson (1956), when there is “no room” left for state regulation. Courts are to look to the pervasiveness of the federal scheme of regulation, the federal interest at stake, and the danger of frustration of federal goals in making the determination as to whether a challenged state law can stand.

In Silkwood v. Kerr-McGee (1984), the court, voting 5–4, found that a $10 million punitive damages award (in a case litigated by famed attorney Gerry Spence) against a nuclear power plant was not impliedly preempted by federal law. Even though the court had recently held that state regulation of the safety aspects of a federally licensed nuclear power plant was preempted, the court drew a different conclusion with respect to Congress’s desire to displace state tort law—even though the tort actions might be premised on a violation of federal safety regulations.

Cipollone v. Liggett Group (1993) was a closely watched case concerning the extent of an express preemption provision in two cigarette labeling laws of the 1960s. The case was a wrongful death action brought against tobacco companies on behalf of Rose Cipollone, a lung cancer victim who had started smoking cigarette in the 1940s. The court considered the preemptive effect on state law of a provision that stated, “No requirement based on smoking and health shall be imposed under state law with respect to the advertising and promotion of cigarettes.” The court concluded that several types of state tort actions were preempted by the provision but allowed other types to go forward.

The Taxing and Spending Powers

Article I, Section 8, provides that Congress has the “Power to lay and collect Taxes, Duties, Imposts, and Excises”. Section 8 further provides that all “Duties, Imposts, and Excises shall be uniform throughout the United States.” The requirement of uniformity refers to the uniformity among the states. Thus, Congress may not tax some states while exempting others.