The U.S. Constitution declares that federal law is “the supreme law of the land.” As a result, when a federal law conflicts with a state or local law, the federal law will supersede the other law or laws. This is commonly known as “preemption.” In practice, it is usually not as simple as this.

Is preemption good or bad?

As a legislative tool, preemption is neither inherently good nor bad. But the misuse and abuse of preemption can be harmful, especially when it limits the ability of cities to respond to the needs of their residents.

Why is preemption bad?

Preemption puts current and future public health at risk by putting a ceiling on the health protection local and state governments can set. ... Ceiling preemption puts an unnecessary roadblock up against policies that protect our communities' health and safety.