William R. Day,
Southern Railway Company v. Greene…
“ We hold, therefore, that to tax the foreign corporation for carrying on business under the circumstances shown, by a different and much more onerous rule than is used in taxing domestic corporations for the same privilege, is a denial of the equal protection of the laws, and the plaintiff being in position to invoke the protection of the 14th Amendment, that such attempted taxation under a statute of the state does violence to the Federal Constitution. ”
