Task of the Supreme Court Under the Clause: Preemption

Clause 2. This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby; any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.


In applying the Supremacy Clause to subjects that have been regulated by Congress, the Court’s primary task is to ascertain whether a challenged state law is compatible with the policy expressed in the federal statute. When Congress legislates with regard to a subject, the extent and nature of the legal consequences of the regulation are federal questions, the answers to which are to be derived from a consideration of the language and policy of the state. If Congress expressly provides for exclusive federal dominion or if it expressly provides for concurrent federal-state jurisdiction, the Court’s task is simplified, though, of course, there may still be doubtful areas in which interpretation will be necessary6 . Where Congress is silent, however, the Court must itself decide whether the effect of the federal legislation is to oust state jurisdiction.7

6 For a discussion of express preemption, see supra Article I: Section 3: Clause 3.

7 Treatment of preemption principles and standards is set out under the Commerce Clause, which is the greatest source of preemptive authority.

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