The state's top court Thursday is to hear Mississippi Attorney General Jim Hood's challenge of the pardons, which he says were unconstitutional because most of the inmates involved didn't meet all of the requirements to receive a pardon, CNN reported.
As he finished his second term as governor, Barbour granted full pardons to more than 200 people convicted of various crimes. Among those pardoned were four convicted murderers who had worked as trusties at the governor's mansion. Their release led to an outpouring of criticism.
Barbour has defended his pardons, saying the former inmates had been rehabilitated.
The court is expected to decide on whether the pardons can be challenged, CNN said. If the court rules against the pardoned criminals, a lower court would be directed to conduct hearings on the cases individually.
Hood has called the pardons "a slap in the face to everyone in law enforcement" and said Barbour "should be ashamed."
"It's just an every minute, constant, in the back of your mind, where is he? What is he doing?" said Mary McAbee, sister of Rick Montgomery, who was shot to death by Joseph Ozment in 1992. Ozment pleaded guilty and was sentenced to life in prison without parole.
"I'm fearful," McAbee told CNN. "He's a cold-blooded murderer to do what he's done, and if he thinks that he may go back to prison, what's he got to lose?"