Almost all the restraints imposed by the Articles of Confederation upon the States could be removed or relaxed by the consent of the Congress to the doing of what was otherwise prohibited. In the first draught of the Constitution, the committee of detail inserted four absolute prohibitions, which could not be removed by Congress itself. These related to the coining of money, the granting of letters of marque and reprisal, the making of treaties, alliances, and confederations, and the granting of titles of nobility. All the other restraints on the States were to be operative or inoperative, according to the pleasure of Congress.[300] Among these were included bills of credit; laws making other things than specie a tender in payment of debts; the laying of imposts or duties on imports; the keeping of troops or ships of war in time of peace; the entering into agreements or compacts with other States, or with foreign powers; and the engaging in war, when not invaded, or in danger of invasion before Congress could be consulted. The enactment of attainder and _ex post facto_ laws, and of laws impairing the obligation of contracts, was not prohibited at all. But when these various subjects came to be regarded more closely, it was perceived that the list of absolute prohibitions must be considerably enlarged. Thus the power of emitting bills of credit, which had been the fruitful source of great evils, must either be taken away entirely, or the contest between the friends and the opponents of paper money would be transferred from the State legislatures to Congress, if Congress should be authorized to sanction the exercise of the power. Fears were entertained that an absolute prohibition of paper money would excite the strenuous opposition of its partisans against the Constitution; but it was thought best to take this opportunity to crush it entirely; and accordingly the votes of all the States but two were given to a proposition to prohibit absolutely the issuing of bills of credit.[301] To the same class of legislation belonged the whole of that system of laws by which the States had made a tender of certain other things than coin legal satisfaction of a debt. By placing this class of laws under the ban of a strict prohibition, not to be removed by the consent of Congress in any case, the mischiefs of which they had been a fruitful source would be at once extinguished. This was accordingly done, by unanimous consent.[302]