When state law conflicts with federal law, things can get dicey. For recent examples, one has to look no further than the issue of marijuana legalization; while marijuana is still illegal under federal drug laws, certain states have legalized its use for medical or recreational purposes.
In order to understand the tension between state and federal laws, it is crucial to understand the Supremacy Clause and the Doctrine of Preemption. The Supremacy Clause is found in Article IV of the U.S. Constitution, stating that federal statutes, treaties, and the Constitution shall be treated as “the supreme law of the land.” Therefore, federal laws have the highest standing in the U.S. legal system, and when federal law conflicts with state law, federal law will always win. The Doctrine of Preemption is derived from the Supremacy Clause, meaning that federal law preempts state laws, even when the laws differ.
The Supremacy Clause also gives the federal government broad powers in the creation, regulation and enforcement of the country’s laws. There are certain express (i.e. enumerated) powers listed in the Constitution as belonging to the federal government, such as the power to declare war, levy taxes, and establish bankruptcy and immigration laws. The federal government also enjoys certain implied powers, or those not mentioned specifically in the Constitution.
Whether the power is express or implied, federal power will always trump state law—unless the federal law is deemed unconstitutional. The Supremacy Clause has taken center stage in a number of court cases, including:
Ware v. Hylton (1796): This was the first case of the U.S. Supreme Court using the Supremacy Clause to strike down a state statute. During the Revolutionary War, Virginia passed a law that allowed the state to confiscate debt payments to British creditors from Virginia citizens. The Supreme Court found that the state law conflicted with the Treaty of Paris, which defended the rights of British creditors.
Martin v. Hunter’s Lessee (1816) and Cohens v. Virginia (1821): In both these rulings, the Supreme Court found that the Supremacy Clause—in conjunction with the judicial system established by Article III of the U.S. Constitution—granted the Supreme Court the power to review state court decisions in issues involving federal law (including interpretation of the Constitution).
Cooper v. Aaron (1958): Arkansas tried to nullify the Supreme Court’s school desegregation decision in Brown v. Board of Education on the grounds of states’ rights. The Supreme Court used the Supremacy Clause to find that federal law controlled and could not be nullified by state statutes or state officials.
Crosby v. National Foreign Trade Council (2000): This case found that even when the state law in question is not directly in conflict with a federal law, the state law can still be found unconstitutional if it “is an obstacle to the accomplishment and execution of Congress’s full purposes and objectives.” Therefore, the Supremacy Clause can still apply, even if there is not a direct conflict between state and federal statutes.