express preemption

Express preemption occurs when Congress explicitly states in a law that federal regulations override or take precedence over conflicting state laws. This means that if there's a direct conflict, the federal law governing the issue will govern, and the state law will be considered invalid or inapplicable in that context. Think of it as Congress clearly signaling that federal rules are the "top priority" for certain matters, ensuring consistency across the country and preventing states from enacting laws that contradict federal policies.