The 22 judges, including one who served as attorney general under former president Bill Clinton, wrote a letter to Perry asking him to postpone the execution of Charles Dean Hood, 39, by 30 days.

"We write because our long experience as jurists and law enforcement officials leads us to believe that justice cannot be served unless the courts are able to consider whether Mr. Hood's conviction and sentence are invalid," they wrote.

Hood is scheduled to be executed on September 10, but a court set a hearing for September 12 to examine defense arguments that he was not given a fair trial.

The court will hear testimony from a prosecutor affirming that his colleague who was prosecuting the case was romantically involved with the judge who sentenced Hood.

"It is an irrevocable wrong to send a man to his death without ever hearing this critical evidence," the 22 judges wrote to Perry.

"We have no doubt that this relationship would have had a significant impact on the ability of the judicial system to accord Mr. Hood a fair and impartial trial," they wrote.