By Article IV, section 4, the United States guarantee to every State a republican form of government and engage to protect each of them against invasion; and on application of the legislature, or of the executive when the legislature can not be convened, against domestic violence.

Of the other parts of the Constitution relating to power, some form restraints on the exercise of the powers granted to Congress and others on the exercise of the powers remaining to the States.  The object in both instances is to draw more completely the line between the two governments and also to prevent abuses by either.  Other parts operate like conventional stipulations between the States, abolishing between them all distinctions applicable to foreign powers and securing to the inhabitants of each State all the rights and immunities of citizens in the several States.

By the fifth article it is provided that Congress, whenever two-thirds of both Houses shall deem it necessary, shall propose amendments, or, on the application of the legislatures of two-thirds of the several States, shall call a convention for proposing amendments, which in either case shall be valid as a part of the Constitution when ratified by the legislatures of three-fourths of the several States, or by conventions in three-fourths thereof, as the one or the other mode may be proposed by Congress:  Provided, That no State, without its consent, shall be deprived of its equal vote in the Senate, and that no amendment which may be made prior to the year 1808 shall affect the first and fourth clauses in the ninth section of the first article.

By the second section of the sixth article it is declared that the Constitution, and laws of the United States which shall be made in pursuance thereof, and all treaties made under the authority of the United States, shall be the supreme law of the land, and that the judges in every State shall be bound thereby, anything in the constitution or laws of any State to the contrary notwithstanding.  This right in the National Government to execute its powers was indispensable to its existence.  If the State governments had not been restrained from encroaching on the powers vested in the National Government, the Constitution, like the Confederation, would soon have been set at naught; and it was not within the limit of the human mind to devise any plan for the accomplishment of the object other than by making a national constitution which should be to the extent of its powers the supreme law of the land.  This right in the National Government would have existed under the Constitution to the full extent provided for by this declaration had it not been made.  To prevent the possibility of a doubt, however, on so important a subject it was proper to make the declaration.