that the paper currency damaged the country much more than the arms of the enemy by land or sea. The feeling was so strong about it in the Federal Convention that the prohibition came near being extended to the national government, but the question was unfortunately left undecided.[25] [Footnote 24: See above, p.175] [Footnote 25: See my _Critical Period of American History_, pp. 168-186, 273-276.] [Sidenote: Powers denied to Congress.] [Sidenote: Bills of attainder.] Some express prohibitions were laid upon the national government. Duties may be laid upon imports but not upon exports; this wise restriction was a special concession to South. Carolina, which feared the effect of an export duty upon rice and indigo. Duties and excises must be uniform throughout the country, and no commercial preference can be shown to one state over another; absolute free trade is the rule between the states. A census must be taken every ten years in order to adjust the representation, and no direct tax can be imposed except according to the census. No money can be drawn from the treasury except "in consequence of appropriations made by law," and accounts must be regularly kept and published. The privilege of the writ of _habeas corpus_ cannot be suspended except "when, in case of rebellion or invasion, the public safety may require it;" and "no bill of attainder, or _ex post facto_ law," can be passed. A bill of attainder is a special legislative act by which a person may be condemned to death, or to outlawry and banishment, without the opportunity of defending himself which he would have in a court of law. "No evidence is necessarily adduced to support it," [26] and in former times, especially in the reign of Henry VIII., it was a formidable engine for perpetrating judicial murders. Bills of attainder long ago ceased to be employed in England, and the process was abolished by statute in 1870. [Footnote 26: Taswell-Langmead, _English Constitutional History_, p. 385.]