Following in the wake of Champion _v._ Ames, Congress has repeatedly brought its prohibitory powers over interstate commerce and communications to the support of certain local policies of the States in the exercise of their reserved powers, thereby aiding them in the repression of the liquor traffic,[501] of traffic in game taken in violation of State laws,[502] of commerce in convict-made goods,[503] of the white slave traffic,[504] of traffic in stolen motor vehicles,[505] of kidnapping,[506] of traffic in stolen property,[507] of racketeering,[508] of prize-fight films or other pictorial representation of encounters of pugilists.[509] The conception of the Federal System on which the Court based its validation of this legislation was stated by it in 1913 in sustaining the Mann "White Slave" Act in the following words: "Our dual form of government has its perplexities, State and Nation having different spheres of jurisdiction, * * *, but it must be kept in mind that we are one people; and the powers reserved to the States and those conferred on the Nation are adapted to be exercised, whether independently or concurrently, to promote the general welfare, material, and moral."[510] At the same time, the Court made it plain that in prohibiting commerce among the States, Congress was equally free to support State legislative policy or to devise a policy of its own. "Congress," it said, "may exercise this authority in aid of the policy of the State, if it sees fit to do so. It is equally clear that the policy of Congress acting independently of the States may induce legislation without reference to the particular policy or law of any given State. Acting within the authority conferred by the Constitution it is for Congress to determine what legislation will attain its purposes. The control of Congress over interstate commerce is not to be limited by State laws."[511] HAMMER _v._ DAGENHART