Control over criminal law is an essential characteristic of sovereignty. Within a federal system, the division of sovereignty complicates responsibilities for law enforcement. This discussion of criminal law in the United States exemplifies how judicial review can be used to re-organize the arrangement of sovereign powers. Much of the U.S. Supreme Court's reputation for the expansion of rights rests on its criminal procedure decisions of the 1960's, most notably those dealing with arrest, search and seizure, and confessions. Generally, the Supreme Court has been reluctant to address substantive criminal law of the states; but its few decisions on such matters as abortion and sodomy have brought about major social changes. In both areas, the Court's most important decisions have been highly publicized and have generally weakened the powers of the individual states. Less visible to the public has been the struggle in the Court over the tremendous expansion of a federal criminal law under a Constitution which withholds a national police power from the central government. In large part, Congress's expansion of federal criminal power has been in response to the Court's weakening of the criminal powers of the individual states.