When Does Federal Law Preempt State Law?

The U.S. Constitution declares that federal law is “the supreme law of the land.” As a result, when a federal law conflicts with a state or local law, the federal law will supersede the other law or laws. This is commonly known as “preemption.” In practice, it is usually not as simple as this. Determining whether federal law preempts state law requires an extensive analysis. Congress can include specific language in a statute that preempts state law, but even in the absence of such language, preemption could be implied by other factors. The U.S. Supreme Court has established requirements for preemption of state law. Meanwhile, an Executive Order issued by President Clinton in the late 1990s addresses preemption by federal regulations.

The Supremacy Clause of the U.S. Constitution

Under the Supremacy Clause, found in Article VI, section 2 of the U.S. Constitution, both the Constitution and federal law supersede state laws. Article I, section 8 of the Constitution defines the powers of the U.S. Congress. It grants some powers exclusively to Congress, such as legislation regarding immigration, bankruptcy, and currency. States do not have the authority to create their own immigration or bankruptcy systems, or to mint their own currency.

The states share some of the powers granted to Congress by section 8, such as the “power to lay and collect taxes.” Congress has authority over certain matters that cross state lines, while states have authority over matters within their own borders. Preemption can arise in any area over which Congress has authority, but it is most often an issue in areas in which Congress and the states share authority.

The Preemption Doctrine

The Supreme Court described the preemption doctrine in Altria Group v. Good, 555 U.S. 70 (2008): “[S]tate laws that conflict with federal law are without effect.” The decision discussed the difference between express and implied preemption, and it identified ways to determine whether Congress intended federal law to preempt state law. The Court also cautioned that, when evaluating evidence of Congressional intent, courts should err on the side of state rather than federal authority.

Express Preemption

When Congress declares that a statute preempts federal law, this is known as “express preemption.” This usually involves a preemption clause in the statute. As mentioned earlier, if a preemption clause is in any way ambiguous, the Supreme Court’s ruling in Altria directs courts to consider the ambiguity in favor of state law. This includes evaluating whether the state law at issue falls within the scope of what Congress intended federal law to preempt.

In Arizona v. United States, 567 U.S. 387 (2012), the Supreme Court held that federal immigration law preempted a state law penalizing undocumented immigrants who worked without authorization. The Immigration Reform and Control Act of 1986 contained an express preemption clause, codified at 8 U.S.C. § 1324(h)(2). The court found that Arizona’s law was “an obstacle to the regulatory system Congress chose.”

Implied Preemption

If Congress does not include an express provision for preemption in the text of a statute, a court could still find that the statute preempts state law. Implied preemption can occur when state and federal laws directly conflict with each other, or when federal laws dominate a field that a state law seeks to regulate.

Conflict Preemption

A conflict may occur between federal and state laws when they impose different requirements on a party. This could make it impossible for a party to comply with both federal and state laws, or even put a party in a position in which compliance with one law puts them in violation of the other.

In Sperry v. Florida, 373 U.S. 379 (1963), the Supreme Court examined a conflict between federal patent laws and a state law governing the licensure of attorneys. The U.S. Patent Office had licensed a person as a patent agent, but the State of Florida had found this to be unauthorized practice of law. The Supreme Court ruled that federal law preempted state law with regard to the person’s ability to act as a patent agent in Florida. While Congress did not expressly state that it intended federal patent law to preempt state licensure law, the court held that preemption was “necessary and proper to accomplish” the goals of the patent laws.

Field Preemption

Field preemption may occur when federal laws and regulations have so thoroughly covered a particular field that no room remains for the states. The Arizona decision mentioned earlier is an example of express field preemption based on authority expressly granted to Congress by the Constitution. The Supreme Court has also recognized implied field preemption based on the sheer volume of federal regulations.

In Gade v. National Solid Wastes Management Association, 505 U.S. 88 (1992), the Court ruled that federal laws governing hazardous waste preempted Illinois laws covering the same field. The ruling cited the vast body of regulations promulgated by the Occupational Safety and Health Administration in order to implement the Occupational Safety and Health Act and the Superfund Amendments and Reauthorization Act of 1986.

Rules for Regulatory Preemption

On August 4, 1999, the Clinton administration issued Executive Order 13132, entitled “Federalism.” It outlined a policy for how regulatory agencies of the Executive Branch should approach regulations that might conflict with state law. Section 4 of the order specifically addresses preemption. It states that agencies should restrict their interpretations of their own regulations so that they preempt state law in only three situations:

  1. Congress expressly authorized preemption;
  2. Congress intended preemption, based on “clear evidence”; or
  3. State law conflicts with the regular enforcement or exercise of federal law.

These are still generally accepted as the three main situations in which preemption may occur.