WASHINGTON (Reuters) - The U.S. city of New Haven, Connecticut violated the law by throwing out a promotion exam after it yielded too many qualified white applicants and no acceptable black candidates, the U.S. Supreme Court ruled on Monday in a major civil rights decision.

By a 5-4 vote and splitting along conservative and liberal lines, the justices overturned a ruling for the city by a U.S. appeals court panel that included Judge Sonia Sotomayor, who is President Barack Obama's Supreme Court nominee.

The appeals court's ruling in the New Haven firefighters case is expected to be an important focus of questioning by Republicans at Sotomayor's Senate confirmation hearing scheduled for next month.

(Reporting by James Vicini, Editing by Deborah Charles)