<P> The first clause in this section prevents Congress from passing any law that would restrict the importation of slaves into the United States prior to 1808 . Congress could however, levy a per capita duty of up to ten Spanish milled dollars for each slave imported into the country . This clause was further entrenched into the Constitution by Article V, where it is explicitly shielded from constitutional amendment prior to 1808 . On March 2, 1807, Congress approved legislation prohibiting the importation of slaves into the United States, which went into effect January 1, 1808, the first day permitted by the Constitution . </P> <P> A writ of habeas corpus is a legal action against unlawful detainment that commands a law enforcement agency or other body that has a person in custody to have a court inquire into the legality of the detention . The court may order the person released if the reason for detention is deemed insufficient or unjustifiable . The Constitution further provides that the privilege of the writ of habeas corpus may not be suspended "unless when in cases of rebellion or invasion the public safety may require it". In Ex parte Milligan (1866), the Supreme Court ruled that the suspension of habeas corpus in a time of war was lawful, but military tribunals did not apply to citizens in states that had upheld the authority of the Constitution and where civilian courts were still operating . </P> <P> A bill of attainder is a law by which a person is immediately convicted without trial . An ex post facto law is a law which applies retroactively, punishing someone for an act that was only made criminal after it was done . The ex post facto clause does not apply to civil matters . </P> <P> Section Nine reiterates the provision from Section Two that direct taxes must be apportioned by state populations . This clause was also explicitly shielded from constitutional amendment prior to 1808 by Article V. In 1913, the 16th Amendment exempted all income taxes from this clause . This overcame the ruling in Pollock v. Farmers' Loan & Trust Co. that the income tax could only be applied to regular income and could not be applied to dividends and capital gains . Furthermore, no tax may be imposed on exports from any state . Congress may not, by revenue or commerce legislation, give preference to ports of one state over those of another; neither may it require ships from one state to pay duties in another . All funds belonging to the Treasury may not be withdrawn except according to law . Modern practice is that Congress annually passes a number of appropriations bills authorizing the expenditure of public money . The Constitution requires that a regular statement of such expenditures be published . </P>

Article i section 2 of the u.s. constitution of 1787