The fundamental written instrument of the US government. It replaced the Articles of Confederation (1781–87), a league of sovereign states, with an effective central, national, federal government. Three months’ secret debate among the Founding Fathers at the Federal Constitutional Convention in Philadelphia in 1787 produced a series of modifications to Madison’s original Virginia Plan. The Great Compromise, between large and small states, gave equal representation in the Senate but by population in the House of Representatives. North and South finally agreed to slaves being counted as three-fifths of a person in representation and taxation, continuation of the slave trade until at least 1808, and no taxes on exports. Conflict between state and central power was reconciled by enumerating areas of federal concern. The principle of popular sovereignty with direct biennial election of congressmen was balanced by indirect election of senators and presidents for renewable six- and four-year terms. Within the federal system of executive (President, Vice-President, cabinet, and civil service), legislature (Senate and House of Representatives), and judiciary (Supreme and other federal courts), a series of checks and balances sought to share and divide power between these three components of government. Thus, for instance, the Supreme Court, appointed by the President with Senatorial approval, may declare actions of the executive or legislature unconstitutional, but may not initiate suits or legislation. The 1787 draft required ratification by nine state conventions. Major opposition in Virginia, Massachusetts, and New York came from the anti-Federalist, states’ rights advocates like Patrick Henry or George Clinton. The constitution was defended in the Federalist Papers by James Madison, Alexander Hamilton, and John Jay and came into operation in 1789. Major shortcomings included failure to foresee political parties, initial absence of a Bill of Rights, complexity of electoral arrangements, and frustration of executive initiative. The loose definition of congressional powers and the persuasive influence of federal grants tipped the balance from state to central supremacy. This flexible guide for government has been amended 27 times, most notably to abolish slavery, to add a Bill of Rights, and to establish Black and female enfranchisement.