International Longshoremen's Ass'n, Local 1416 v. Ariadne Shipping Co.

The question presented here is whether the National Labor Relations Act, 49 Stat. 449, as amended, 29 U. S. C. § 151 et seq., pre-empts state jurisdiction to enjoin peaceful picketing protesting substandard wages paid by foreign-flag vessels to American longshoremen working in American ports. The Florida courts held that there was no pre-emption, citing McCulloch v. Sociedad Nacional, 372 U. S. 10 (1963), and lucres Steamship Co. v. International Maritime Workers Union, 372 U. S. 24 (1963). We granted certiorari. 396 U. S. 814 (1969). We reverse.

In 1966 the respondents, a Liberian corporation…