“ The three-judge requirement is a technical one to be narrowly construed, Phillips v. United States, 312 U.S. 246, 251, 61 S.Ct. 480, 483, 85 L.Ed. 800. The statute comes into play only when an injunction is sought 'upon the ground of the unconstitutionality' of a statute. There is no such ground when the constitutional issue presented is essentially fictitious. ”

“ The reasons for convening an extraordinary court are inapplicable in such cases, for the policy behind the three-judge requirement-that a single judge ought not to be empowered to invalidate a state statute under a federal claim-does not apply. ”

“ We have settled beyond question that no State may require racial segregation of interstate or intrastate transportation facilities. Morgan v. Commonwealth of Virginia, 328 U.S. 373, 66 S.Ct. 1050, 90 L.Ed. 1317; Gayle v. Browder, 352 U.S. 903, 77 S.Ct. 145, 1 L.Ed.2d 114; Boynton v. Com. Virginia, 364 U.S. 454, 81 S.Ct. 182, 5 L.Ed.2d 206. The question is no longer open; it is foreclosed as a litigable issue. Section 2281 does not require a three-judge court when the claim that a statute is unconstitutional is wholly insubstantial, legally speaking nonexistent. ”