For questions specific to the United States as a whole, or that span multiple state jurisdictions. If your question is related to a specific state then you should use that state's tag instead (or as well).
In the United States, individual states have significant independence from the federal government, particularly in the area of their respective legal codes (ref. "dual sovereignty"). If your question concerns a specific state jurisdiction, include the tag for that state as well as (or instead of) the "united-states" tag.