Establishing these two classifications of government powers in our federal system left the possibility that both levels of government might claim some powers. In some situations, the exercise of power by one level of government conflicts with the exercise of power by the other level of government. Article 6, paragraph two of the Constitution explains how to resolve these conflicts: "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, anything in the Constitution or laws of any State to the contrary notwithstanding."
This is the supremacy clause of the Constitution, which essentially says that in the event of a conflict in the exercise of federal and state powers, the power of the federal government prevails.
This supremacy clause has given rise to a concept called federal preemption, which is a doctrine that states if federal laws and state laws conflict, the federal law takes precedence over the state law.
The supremacy clause can offer a business the opportunity to avoid a state law that the business finds to be improper, if there is a federal law that addresses the same issue or regulation. Of course, even if that challenge is successful, the business will still have to comply with the federal regulations because the supremacy clause dictates that federal law is the supreme law of the United States.