The Constitution established a federal government of limited powers, limited not only by their explicit and full enumeration in Article 1, § 8, but also by the enumeration (but by no means an exhaustive one) in the Bill of Rights of certain important rights upon which the government must not trespass. Any power exercised by the government which does not fall within the list given in § 8 has been usurped, either from the people themselves or from the states, and being extra-Constitutional, is therefore illegitimate. Now the Bill of Rights is not so much a limit on the powers per se, but rather a limit on the means by which such powers may be exercised.