About: State preemption

In United States law, state preemption is the invalidation of some action by, or the wresting of power from, a portion of the state government (more often than not a municipality or other part of the state government that only exerises power within a certain geographical area such as a county) usually by the state legislature. Preemption is often used when there is a political disagreement between the state legislature and municipal governments. The largest division between the legislature and the government is typically partisan; most state legislatures have been, since 2010, dominated by Republicans, while city governments are typically dominated by Democrats.