w:Supreme Court of the United States, Chicago Rock Island Pacific Railway Company v…
“ As legislation concerning the delivery of cars for the carriage of interstate traffic was clearly a matter of interstate commerce regulation, even if such subject was embraced within that class of powers concerning which the state had a right to exert its authority in the absence of legislation by Congress, it must follow, in consequence of the action of Congress to which we have referred, that the power of the state over the subject-matter ceased to exist from the moment that Congress exerted its paramount and all-embracing authority over the subject. ”
