The ruling could alter employment practices nationwide and make it harder to prove discrimination when there is no evidence it was intentional.

New Haven was wrong to scrap a promotion exam because no African-Americans and only two Hispanic firefighters were likely to be made lieutenants or captains based on the results, the court said Monday in a 5-4 decision. The city said that it had acted to avoid a lawsuit from minorities.

The ruling could give Sotomayor's critics fresh ammunition two weeks before her Senate confirmation hearing. Conservatives say it shows she is a judicial activist who lets her own feelings color her decisions. On the other hand, liberal allies say her stance in the case demonstrates her restraint and unwillingness to go beyond established precedents.

Coincidentally, the court may have given a boost to calls for quick action on her nomination.

The court said it will return Sept. 9 to hear a second round of arguments in a campaign finance case, and with Justice David Souter retiring there would be only eight justices unless Sotomayor has been confirmed by then.

In Monday's ruling, Justice Anthony Kennedy said, "Fear of litigation alone cannot justify an employer's reliance on race to the detriment of individuals who passed the examinations and qualified for promotions." He was joined in the majority by Chief Justice John Roberts and Justices Samuel Alito, Antonin Scalia and Clarence Thomas.