A court of competent jurisdiction in Wisconsin gave the plaintiff a judgment against the defendants an Illinois corporation, for truces levied by Wisconsin upon income earned in that state. A federal district court in Illinois, relying on a theory that one state should not undertake to enforce the revenue laws of a sister state, dismissed an action on the judgment instituted by the plaintiff. The plaintiff appealed. Held, principles of comity and the "full faith and credit" clause of the Federal Constitution require that the action be entertained. Milwaukee County v. M. E. White Co., 296 U.S. 268, 56 S. Ct. 229 (1935).