Lyndon, a citizen of Maryland, obtains a federal license to operate a commercial fishing boat in a certain area off the Maryland coast. The Maryland state legislature enacts a law that bans all commercial fishing in that area. The state law most likely violates

Answer: the supremacy clause

Explanation: The Supremacy Clause of the American Constitution (Article VI, Clause 2) states that the Constitution, the federal laws enacted in accordance with it and the agreements made under its jurisdiction represent the "supreme law of the country" and therefore take precedence over any opposing state's laws.

Essentially, it is a clash-of-laws rule that states that some statutory acts take precedence against any state act that clash with federal statute, but that statute is invalid when federal law clashes with the Constitution.