To implement these abstract ideas, the Founders established three branches of government�the executive, the legislative, and the judicial. The functions of these branches are described in the first three articles of the Constitution.
Article I is the longest article in the Constitution; it establishes the national legislature called Congress. The Founders divided Congress into a Senate and a House of Representatives because they were afraid of placing too much authority in any one institution. Among other powers, Congress collects taxes, provides for the common defense (meaning that the federal government, not just the states, provides resources for the protection and security of the United States), regulates commerce, raises armies, and declares war. In addition, Article I contains the �necessary and proper clause,� which authorizes Congress to pass any law that it thinks is necessary to carry out its constitutional duties. This provision is very important because it allows Congress to react to situations that may not have existed when the Constitution was written.
Article II establishes an executive department headed by a president and vice president. The article further describes the powers of the offices, the manner of election, and the qualifications for office. Of special significance is the president�s constitutional role as commander of the nation�s armed forces, which assures civilian control over the military. Because the president is the head of the armed forces and only Congress can declare war, the authority of the military is diffused and its power to make decisions is restrained. The Constitution also grants the president the authority to make treaties with other nations. However, to limit abuse of this power, the Constitution requires treaties to be ratified by two-thirds of the Senate.
Article III directs that the federal judicial power be placed in a Supreme Court and in other courts as directed by Congress. This brief article also lists the kinds of cases that fall specifically under the jurisdiction of the federal courts.
