WASHINGTON — The Supreme Court ruled today that white firefighters in New Haven, Conn., were unfairly denied promotions because of their race, reversing a decision that high court nominee Sonia Sotomayor endorsed as an appeals court judge.

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 today in a 5-4 decision. The city said that it had acted to avoid a lawsuit from minorities.

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

"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," Justice Anthony Kennedy said in his opinion for the court.