Determining whether state or federal law takes precedence in a given situation was a central debate among the drafters of the U.S. Constitution, and it continues to be a critical legal issue. Some powers are reserved to the states, in other areas the Congress can overrule state law, and in some areas neither the states nor the Congress may freely make law. The Constitution determines which sovereign, if any, may make laws on a topic. The problem is that the Constitution is a general document, drafted over 200 years ago. Fortunately, the Constitution created the U.S. Supreme Court as a referee between the Congress and the states. Shortly after its creation, the Supreme Court reserved to itself the right to determine the meaning of the Constitution. It is through this power of interpretation that the Court can declare that a law is unconstitutional—that is, that it violates the protections that are part of the Constitution.

Consistent with the states’ desire for the federal government to deal with foreign powers and to control disputes between the states, the Constitution gives the federal government sole authority over the regulation of interstate commerce, foreign affairs, and the power to declare war. Amendments adopted after the Civil War gave the federal government additional powers to protect individual rights. The remaining powers are either shared with, or retained solely by the states. In some areas this sharing of power can result in a health care practitioner facing both state and federal sanctions for a given activity. For example, the federal law criminalizes kickbacks to affect the referral of Medicare patients. Some states also criminalize these same violations. A health care practitioner who paid such kickbacks could be prosecuted by both the federal and state governments for the same transactions. Health law issues usually involve the federal power to regulate interstate commerce, and the important shared power is the police power to protect the public health and safety.