“ But the statute does recognize certain rights in the public to have unimpeded for a time production in industries vital to the national health or safety. It makes the United States the guardian of these rights in litigation. Cf. United States v. American Bell Tel. Co., 128 U.S. 315, 370, 9 S.Ct. 90, 98, 32 L.Ed. 450; Sanitary District of Chicago v. United States, 266 U.S. 405, 45 S.Ct. 176, 69 L.Ed. 352. The availability of relief, in the common judicial form of an injunction, depends on findings of fact, to be judicially made. ”

“ We need not resolve this question, for we think the judgment below is amply supported on the ground that the strike imperils the national safety. Here we rely upon the evidence of the strike's effect on specific defense projects; we need not pass on the Government's contention that 'national safety' in this context should be given a broader construction and application. ”