|Justice Brett Kavanaugh wrote the court's majority opinion. Justices Clarence Thomas and Neil Gorsuch dissented.
In Flowers' sixth trial, the jury was made up of 11 whites and one African American. District Attorney Doug Evans struck five black prospective jurors.
In the earlier trials, three convictions were tossed out, including one when the prosecutor improperly excluded African Americans from the jury. In the second trial, the judge chided Evans for striking a juror based on race. Two other trials ended when jurors couldn't reach unanimous verdicts.
"The numbers speak loudly," Kavanaugh said in a summary of his opinion that he read in the courtroom, noting that Evans had removed 41 of the 42 prospective black jurors over the six trials. "We cannot ignore that history."
In dissent, Thomas called Kavanaugh's opinion "manifestly incorrect" and wrote that Flowers presented no evidence whatsoever of purposeful race discrimination."
Flowers has been in jail more than 22 years, since his arrest after four people were found shot to death in a furniture store in Winona, Mississippi, in July 1996.
Flowers was arrested several months later, described by prosecutors as a disgruntled former employee who sought revenge against the store's owner because she fired him and withheld most of his pay to cover the cost of merchandise he damaged. Nearly $300 was found missing after the killings.