It was formed by the States; that is, by the people in each of the States acting in their highest sovereign capacity, and formed, consequently, by the same authority which formed the State constitutions. ...  Nor is the Government of the United States, created by the Constitution, less a government, in the strict sense of the term, within the sphere of its powers than the governments created by the constitutions of the States are within their several spheres.  It is, like them, organized into legislative, executive, and judiciary departments.  It operates, like them, directly on persons and things, and, like them, it has at command a physical force for executing the powers committed to it.

It was intended to be perpetual, and not to be annulled at the pleasure of any one of the contracting parties.  The old Articles of Confederation were entitled “Articles of Confederation and Perpetual Union between the States,” and by the thirteenth article it is expressly declared that “the articles of this Confederation shall be inviolably observed by every State, and the Union shall be perpetual.”  The preamble to the Constitution of the United States, having express reference to the Articles of Confederation, recites that it was established “in order to form a more perfect union.”  And yet it is contended that this “more perfect union” does not include the essential attribute of perpetuity.

But that the Union was designed to be perpetual appears conclusively from the nature and extent of the powers conferred by the Constitution on the Federal Government.  These powers embrace the very highest attributes of national sovereignty.  They place both the sword and the purse under its control.  Congress has power to make war and to make peace, to raise and support armies and navies, and to conclude treaties with foreign governments.  It is invested with the power to coin money and to regulate the value thereof, and to regulate commerce with foreign nations and among the several States.  It is not necessary to enumerate the other high powers which have been conferred upon the Federal Government.  In order to carry the enumerated powers into effect, Congress possesses the exclusive right to lay and collect duties on imports, and, in common with the States, to lay and collect all other taxes.

But the Constitution has not only conferred these high powers upon Congress, but it has adopted effectual means to restrain the States from interfering with their exercise.  For that purpose it has in strong prohibitory language expressly declared that—­

No State shall enter into any treaty, alliance, or confederation; grant letters of marque and reprisal; coin money; emit bills of credit; make anything but gold and silver coin a tender in payment of debts; pass any bill of attainder, ex post facto law, or law impairing the obligation of contracts.

Moreover—­

  No State shall without the consent of the Congress lay any imposts
  or duties on imports or exports, except what may be absolutely
  necessary for executing its inspection laws.