<P> Under the Compact Clause, states may not, without the consent of Congress, keep troops or armies during times of peace . They may not enter into alliances nor compacts with foreign states, nor engage in war unless invaded . States may, however, organize and arm a militia according to the discipline prescribed by Congress . (Article I, Section 8, enumerated powers of Congress .) The National Guard, whose members are also members of the militia of the United States as defined by 10 U.S.C. § 311, fulfill this function, as do persons serving in State Militias with federal oversight under 32 U.S.C. § 109 . </P> <P> The idea of allowing Congress to have say over agreements between states traces back to the numerous controversies that arose between various colonies . Eventually compromises would be created between the two colonies and these compromises would be submitted to the Crown for approval . After the American Revolutionary War, the Articles of Confederation allowed states to appeal to Congress to settle disputes between the states over boundaries or "any cause whatever". The Articles of Confederation also required Congressional approval for "any treaty or alliance" in which a state was one of the parties . </P> <P> There have been a number of Supreme Court cases concerning what constitutes valid congressional consent to an interstate compact . In Virginia v. Tennessee, 148 U.S. 503 (1893), the Court found that some agreements among states stand even when lacking the explicit consent of Congress . (One example the court gave was a state moving some goods from a distant state to itself, it would not require Congressional approval to contract with another state to use its canals for transport .) According to the Court, the Compact Clause requires congressional consent only if the agreement among the states is "directed to the formation of any combination tending to the increase of political power in the States, which may encroach upon or interfere with the just supremacy of the United States". The congressional consent issue is at the center of the current debate over the constitutionality of the not yet effective National Popular Vote Interstate Compact entered into by several states plus the District of Columbia . </P>

Describe the first three articles of the us constitution. what is the main job of each