Alabama Civil Procedure and Constitutional Law Practice Test 2026 – Complete Exam Prep

The key concept is that preemption under the Supremacy Clause comes from federal law that occupies a field. For a state law to be preempted, Congress must have validly regulated in that area—i.e., Congress has enacted a federal statute within its constitutional powers that comprehensively governs the field (expressly or by field preemption). Only if Congress has created that federal regulation does the federal rule take precedence over conflicting state rules.

Executive orders or a Supreme Court ruling aren’t the source of that congressional action. An executive order isn’t a statute, so it doesn’t by itself establish preemption. A Supreme Court ruling interprets and applies law, but the question asks what Congress must have done. A state referendum is a decision by the state, not federal action. So the correct idea is that Congress must have validly regulate in the field to preempt conflicting state law.