After demonstrating most convincingly that the clauses of the Constitution which vested in Congress the power to prohibit the migration of persons into the United States after 1808 and to regulate commerce between the Commonwealths could not be interpreted as giving Congress the power to prevent the transportation of slaves from one Commonwealth into another, Mr. Holmes attacked the fundamental proposition upon which Mr. Taylor relied, the proposition that if Congress could admit, it could refuse to admit, and if it could admit or refuse to admit at pleasure, it could admit upon conditions. Mr. Holmes contended that the power to determine whether slavery should exist or not in any community was possessed by each Colony before the Revolution, and by each "State" after the Revolution, and that the Constitution of 1787 had not deprived the "States" of it, but had recognized it as belonging to each of them exclusively; that new "States" admitted by Congress into the Union must have all the rights, and be subject to all the duties, which the original "States" possessed, on the one side, and were obligated to discharge, on the other; that Congress could not increase the powers of the general {81} Government within the new Commonwealths by selling the Territories a license to the Commonwealth status, and taking the pay for it in powers to be exercised by the general Government in the new Commonwealths, which that Government could not, by the Constitution, exercise within the original Commonwealths; and that if Congress assumed to exercise such power, and the people of the Territory seeking the Commonwealth status should even accept the imposed condition, the new Commonwealth had the right and the power to free itself from the condition, and the Congress was powerless to prevent it. [Sidenote: Mr. McLane's argument against the amendment.]