502us2$26D 01-22-99 08:32:58 PAGES OPINPGT 388 RUFO v. INMATES OF SUFFOLK COUNTY JAIL Opinion of the Court 2 A consent decree must of course be modified if, as it later turns out, one or more of the obligations placed upon the parties has become impermissible under federal law. But modification of a consent decree may be warranted when the statutory or decisional law has changed to make legal what the decree was designed to prevent. This was the case in Railway Employes v. Wright, 364 U. S. 642 (1961). A railroad and its unions were sued for violating the Railway Labor Act, 45 U. S. C. § 151 et seq., which banned discrimination against nonunion employees, and the parties entered a consent decree that prohibited such discrimination. Later, the Railway Labor Act was amended to allow union shops, and the union sought a modification of the decree. Although the amendment did not require, but purposely permitted, union shops, this Court held that the union was entitled to the modification because the parties had recognized correctly that what the consent decree prohibited was illegal under the Railway Labor Act as it then read and because a “court must be free to continue to further the objectives of th[e] Act when its provisions are amended.” Railway Employes, supra, at 651. See also Firefighters v. Stotts, 467 U. S. 561, 576, and n. 9, 583, n. 17 (1984). Petitioner Rapone urges that, without more, our 1979 decision in Bell v. Wolfish, 441 U. S. 520, was a change in law requiring modification of the decree governing construction of the Suffolk County Jail. We disagree. Bell made clear what the Court had not before announced: that double celling is not in all cases unconstitutional. But it surely did not cast doubt on the legality of single celling, and petitioners were undoubtedly aware that Bell was pending when they signed the decree. Thus, the case must be judged on the basis that it was immaterial to petitioners that double celling might be ruled constitutional, i. e., they preferred even in that event to agree to a decree which called for providing only single cells in the jail to be built.