The U.S. legal system is modeled largely on the British common law system. There are, primarily, two distinct court systems in the United States: the state systems of each of the 50 states, and the federal system. Courts in the federal and various state systems are governed by the relevant constitution. The federal constitution grants certain powers to the federal government (including the federal judiciary) and reserves the rest for the states (except to the extent that it prohibits the states from acting in certain ways). Generally speaking, state courts are courts of general jurisdiction; federal courts are courts of limited jurisdiction. The most common bases for invoking federal jurisdiction are where the case involves a question of federal law, or where the dispute is between citizens of different states.