Legal Definitions - Supremacy Clause

The Supremacy Clause is a fundamental principle found in Article VI, Paragraph 2 of the U.S. Constitution. It establishes that the U.S. Constitution, federal laws passed by Congress, and treaties made under the authority of the United States are the "supreme Law of the Land." This means that in any conflict between federal law and state law, the federal law takes precedence. States cannot pass laws that contradict federal law, nor can they interfere with the federal government's exercise of its constitutional powers or assume functions exclusively assigned to the federal government.

Examples:

• Example 1: Environmental Regulations

  Imagine the U.S. Congress passes a comprehensive federal law setting strict national standards for clean air, including specific limits on industrial emissions. A particular state then enacts its own law that allows factories within its borders to emit pollutants at a higher level than the federal standard. Under the Supremacy Clause, the federal clean air law would override the state's less stringent regulation. The state would be prohibited from enforcing its own law, and factories would be required to comply with the stricter federal standards, ensuring a uniform level of environmental protection across the nation.

• Example 2: Immigration Policy

  Federal law, established by Congress, dictates who can legally enter, reside in, and become a citizen of the United States. If a state were to pass a law creating its own separate system for granting legal residency to individuals who do not meet federal immigration criteria, or if it attempted to deport individuals in a manner inconsistent with federal procedures, that state law would be invalid. The Supremacy Clause ensures that federal immigration laws are the supreme authority, preventing states from creating their own conflicting or contradictory immigration policies.

• Example 3: Interstate Commerce and Transportation

  Consider federal regulations that mandate specific safety features and operational standards for commercial trucks traveling across state lines. A state might then pass a law requiring different, more burdensome safety equipment or imposing conflicting weight limits for trucks using its highways, even if those trucks are part of interstate commerce. Due to the Supremacy Clause, the federal regulations would take precedence. The state could not enforce its conflicting rules because they would interfere with the federal government's authority to regulate interstate commerce and ensure consistent transportation standards nationwide.