The Carolene footnote is cited in Thornhill v. Alabama, 310 U.S. 88, 95, 60 S.Ct. 736, 741, 84 L.Ed. 1093, in an opinion which thus proceeds: 'Mere legislative preference for one rather than another means for combating substantive evils, therefore, may well prove an inadequate foundation on which to rest regulations which are aimed at or in their operation diminish the effective exercise of rights