69. Within their respective jurisdictions the United States and the several States have power to regulate commerce. The power over commerce, in either jurisdiction, is exercisable within the principle of self-preservation. Whatsoever exercise of this power is essential to the existence of either government belongs to that government and cannot be repugnant to the other, that is, under the dual system of American constitutional government. Simple as this principle may seem, its practical application in defining the two jurisdictions, or the authority of either government, involves all the issues in American constitutional law, and the decisions of the American judiciary in cases arising under the commerce clause of the Constitution.
A notable instance of the authority given by the commerce clause is the power of Congress, over the transportation of the mails, to prevent “any unlawful and forcible interference” with them. “The strong arm of the government may be put forth to brush away all obstructions to the freedom of interstate commerce or the transportation of the mails”; “the United States have a property in the mails.” The contents of the mail-bags—that is, matter, lawfully mailable—are commerce in the sense in which that word is used in the Constitution.
Constitutional provisions do not change, but their operation extends to new matters as the modes of business and the habits of life of the people vary with each succeeding generation. The law of the common carrier is the same to-day as when transportation on land was by coach and wagon, and on water by canal boat and sailing vessel, yet in its actual operation it touches and regulates transportation by modes then unknown, the railroad train and the steamship. Just so is it with the grant to the national government of power over interstate commerce. The Constitution has not changed. The power is the same. But it operates to-day upon modes of interstate commerce unknown to the fathers, and it will operate with equal force upon any new modes of such commerce which the future may develop.[181]
Under the commerce clause Congress
may enact such legislation as shall declare void and prohibit the performance of any contract between individuals or corporations where the natural and direct effect of such a contract will be, when carried out, to directly, and not as a mere incident to other and innocent purposes regulate to any substantial extent interstate commerce.
And “interstate” also includes “foreign commerce.”[182]
All the decisions
illustrate the principle that Congress in the exercise of its paramount power may prevent the common instrumentalities of interstate and intrastate commercial intercourse from being used in their intrastate operations to the injury of interstate commerce. This is not to say that Congress possesses the authority to regulate the internal commerce of a State, as such, but that it does possess the power to foster and protect interstate commerce, and to take all measures necessary or appropriate to that end, although intrastate transactions of interstate carriers may thereby be controlled.[183]