Texas Department of Criminal Justice, Associated Press
This undated handout photo provided by the Texas Department of Criminal Justice shows Duane Buck. Defense attorneys are calling on Texas Gov. Rick Perry to halt the execution of Buck who is scheduled to be put to death Thursday because jurors heard testimony during sentencing in his 1997 trial that blacks are more likely to pose future dangers to the public.

HUNTSVILLE, Texas — The U.S. Supreme Court has halted the execution of a black man convicted of a double murder in Texas 16 years ago after his lawyers contended his sentence was unfair because of a question asked about race during his trial.

Forty-eight-year-old John Buck was scheduled for lethal injection Thursday evening.

At issue was a psychologist's testimony that black people were more likely to commit violence.

A similar request to block the punishment was made to Texas Gov. Rick Perry. Perry is the Republican frontrunner for the GOP presidential nomination and his actions have now come under closer scrutiny.