Frank Murphy

“ To limit our inquiry to respondents' single standard would restrict us to unreality. For Congress is often explicit when it wishes state laws to conclude federal prosecution, to avoid the double punishment possible in a federal system. ”

“ Only in Wichita and Denver was regulation attempted, and its extent in Wichita is not at all clear.↑ Respondents ignore practical differences when they rely upon the Southern R. Co. case, supra, which invalidated state regulation of grab-irons on railroad cars moving in interstate commerce. The individual state's interest in the manner its residents use its own highways can hardly be compared with the time-honored I.C.C. control over the nation's traditional avenues of interstate transportation, the railroads. ”

“ Congress has provided certain limited penalties, 'and a state law is not to be declared a help because it attempts to go farther than Congress has seen fit to go,' Varnville, supra, 237 U.S. at page 604, 35 S.Ct. at page 717, 59 L.Ed. 1137, Ann.Cas.1916D, 333-that is, if Congress has 'occupied the field.' But the fact of identity does not mean the automatic invalidity of State measures. Coincidence is only one factor in a complicated pattern of facts guiding us to congressional intent. ”

“ When the I.C.C. removed the federal exemption, it mentioned twelve cities, other than Los Angeles and San Francisco, in which the problem was particularly acute. [11] Of these twelve cities, only two were located in states which attempted regulation of the kind of transportation we are now considering. [12] Such striking absence of state law in states where the problem was recognized as serious by the I.C.C. clearly demonstrates a purpose to provide rather than displace local rules-to fill a void rather than nationalize a single rule. ”

“ We restate the familiar because respondents would have us pronounce an additional rule: that when Congress has made specified activity unlawful, 'coincidence is as ineffective as opposition,' and State laws 'aiding' enforcement are invalid. Respondents seem to argue that this is as fundamental as the rule of conflict with national authority, and that it rests upon wholly independent premis s. ”

“ Discussion in debate and hearings is largely descriptive. See, e.g., Hearings before Subcommittee of House Committee on Interstate and Foreign Commerce on H.R. 5262 and H.R. 6016, 74th Cong., 1st Sess., pp. ”