Studying criminal justice in the United States is particularly challenging because of the nation’s complex structure: the United States is not a unitary jurisdiction but rather a federation of fifty states joined under the terms of the Constitution of the United States, and the administration of criminal justice is shared among the federal government and the various states. As a result, one cannot speak of “American criminal law” or “American criminal procedures.” Rather, there are fifty-one sets of laws and procedures—one for each state, and one for the federal government. To be sure, the criminal procedures of the various states and of the federal government share many similarities and in general are distinctively different from procedures used in continental Europe and elsewhere, but it is important to remember that the laws, procedures, and practices on any point may differ between one jurisdiction and another.