Lincoln covered this subject in one of his comprehensive statements that cannot be quoted too often. He said in the first inaugural:

"A majority held in restraint by constitutional checks and limitations and always changing easily with deliberate changes of popular opinion and sentiments the only true sovereign of a free people. Whoever rejects it does of necessity fly to anarchy or despotism."

Rules of limitation, however, are useless unless they are enforced. The reason for restraining rules arises from a tendency to do the things prohibited. Otherwise no rule would be needed. Against all practical rules of limitation—all rules limiting official conduct, there is a constant pressure from one side or the other. Honest differences of opinion as to the extent of power, arising from different points of view make this inevitable, to say nothing of those weaknesses and faults of human nature which lead men to press the exercise of power to the utmost under the influence of ambition, of impatience with opposition to their designs, of selfish interest and the arrogance of office. No mere paper rules will restrain these powerful and common forces of human nature.

The agency by which, under our system of government, observance of constitutional limitation is enforced is the judicial power. The constitution provides that "This constitution, and the laws of the United States which shall be made in pursuance thereof, and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the constitution or laws of any state to the contrary notwithstanding." Under this provision an enactment by Congress not made in pursuance of the constitution, or an enactment of a state contrary to the constitution, is not a law. Such an enactment should strictly have no more legal effect than the resolution of any private debating society. The constitution also provides that the judicial power of the United States shall extend to all cases in law and equity arising under the constitution and laws of the United States. Whenever, therefore, in a case before a Federal court rights are asserted under or against some law which is claimed to violate some limitation of the constitution, the court is obliged to say whether the law does violate the constitution or not, because if it does not violate the constitution the court must give effect to it as law, while if it does violate the constitution it is no law at all and the court is not at liberty to give effect to it. The courts do not render decisions like imperial rescripts declaring laws valid or invalid. They merely render judgment on the rights of the litigants in particular cases, and in arriving at their judgment they refuse to give effect to statutes which they find clearly not to be made in pursuance of the constitution and therefore to be no laws at all. Their judgments are technically binding only in the particular case decided, but the knowledge that the court of last resort has reached such a conclusion concerning a statute, and that a similar conclusion would undoubtedly be reached in every case of an attempt to found rights upon the same statute, leads to a general acceptance of the invalidity of the statute.

There is only one alternative to having the courts decide upon the validity of legislative acts, and that is by requiring the courts to treat the opinion of the legislature upon the validity of its statutes, evidenced by their passage, as conclusive. But the effect of this would be that the legislature would not be limited at all except by its own will. All the provisions designed to maintain a government carried on by officers of limited powers, all the distinctions between what is permitted to the national government and what is permitted to the state governments, all the safeguards of the life, liberty and property of the citizen against arbitrary power, would cease to bind Congress, and on the same theory they would cease also to bind the legislatures of the states. Instead of the constitution being superior to the laws the laws would be superior to the constitution, and the essential principles of our government would disappear. More than one hundred years ago, Chief Justice Marshall, in the great case of Marbury vs. Madison, set forth the view upon which our government has ever since proceeded. He said:

"The powers of the legislature are defined and limited; and that those limits may not be mistaken or forgotten, the constitution is written. To what purpose are powers limited, and to what purpose is that limit committed to writing, if these limits may, at any time, be passed by those intended to be restrained? The distinction between a government with limited and unlimited powers is abolished, if those limits do not confine the persons on whom they are imposed, and if acts prohibited and acts allowed are of equal obligation. It is a proposition too plain to be contested, that the constitution controls any legislative act repugnant to it; or that the legislature may alter the constitution by an ordinary act.

"Between these alternatives, there is no middle ground. The constitution is either a superior, paramount law, unchangeable by ordinary means, or it is on a level with ordinary legislative acts, and, like other acts, is alterable when the legislature shall please to alter it. If the former part of the alternative be true, then a legislative act, contrary to the constitution, is not law: if the latter part be true, then written constitutions are absurd attempts, on the part of the people, to limit a power, in its own nature, inimitable.

"Certainly, all those who have framed written constitutions contemplate them as forming the fundamental and paramount law of the nation, and consequently, the theory of every such government must be, that an act of the legislature, repugnant to the constitution, is void. This theory is essentially attached to a written constitution, and is, consequently, to be considered by this court as one of the fundamental principles of our society."

And of the same opinion was Montesquieu who gave the high authority of the Esprit des Lois to the declaration that

"There is no liberty if the power of judging be not separate from the legislative and executive powers; were it joined with the legislative the life and liberty of the subject would be exposed to arbitrary control."