The Supreme Court threw out the death sentence and conviction in a Louisiana murder case Wednesday, citing racial prejudice in the actions of a prosecutor who called the murder trial his "O.J. Simpson case" and kept blacks off the jury.

By a 7-2 vote, the justices said state prosecutor Jim Williams improperly excluded blacks from the jury that convicted Allen Snyder of killing his estranged wife's companion. Snyder is black and the jurors were white.

Justice Samuel Alito, writing for the majority, said the trial judge should have blocked Williams from striking a black juror. Alito's opinion made no mention of Simpson.

Justices Clarence Thomas and Antonin Scalia dissented. Thomas said he would not "second-guess" the judge.

During jury selection in the trial, Williams disqualified all five blacks in the pool of prospective jurors. The Supreme Court ruled in 1986 that prosecutors may not exclude people from a jury solely because of their race. The court already had sent Snyder's case back to the Louisiana courts following a ruling in 2005 that bolstered the prohibition on race bias in jury selection.

The prosecutor's explanation for striking a prospective black juror was "suspicious," said Alito. The prospective juror's supervisor said he did not think a schedule conflict between the upcoming trial and the prospective juror's work would be a problem.

In contrast, the prosecutor accepted white jurors who disclosed conflicting obligations "that appear to have been at least as serious as" the prospective black juror who was excused, Alito wrote.