46 U.S.C. § 8501: State regulation of pilots

Except as otherwise provided in this subtitle, pilots in the bays, rivers, harbors, and ports of the United States shall be regulated only in conformity with the laws of the States. The master of a vessel entering or leaving a port on waters that are a boundary between 2 States, and that is required to have a pilot under this section, may employ a pilot licensed or authorized by the laws of either of the 2 States. A State may not adopt a regulation or provision that discriminates in the rate of pilotage or half-pilotage between vessels sailing between the ports of one State and vessels sailing between the ports of different States, or against vessels because of their means of propulsion, or against public vessels of the United States. is propelled by machinery and subject to inspection under part B of this subtitle; or is subject to inspection under chapter 37 of this title. Any regulation or provision violating this section is void.