The supremacy clause, which is found in Article VI, Section 2 of the constitution and reads as follows: This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.
Additionally, the 14th amendment goes further by stating: No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States.