[512] 247 U.S. 251 (1918).
[513] 39 Stat. 675 (1916).
[514] 247 U.S. at 275.
[515] Ibid. 271-272.
[516] 267 U.S. 432 (1925).
[517] 41 Stat. 324 (1919).
[518] 267 U.S. at 436-439. See also Kentucky Whip & Collar Co. v. Illinois C.R. Co., 299 U.S. 334 (1937).
[519] United States v. Darby, 312 U.S. 100, 116-117 (1941).
[520] Roland Co. v. Walling, 326 U.S. 657, 669 (1946).
[521] Polish Alliance v. Labor Board, 322 U.S. 643, 650 (1944). Cf. the opinion of Chief Justice Vinson for the Court in Bus Employees v. Wisconsin Board, 340 U.S. 383 (1951).