NEW ORLEANS (AP) — The conviction of Louisiana inmate Albert Woodfox in the 1972 death of a prison guard is at issue before a federal appeals court in New Orleans.

The 5th U.S. Circuit Court of Appeals is hearing arguments Tuesday on whether Woodfox’s conviction in the death of guard Brent Miller should be should be re-instated.

U.S. District Judge James Brady agreed last year with Woodfox’s claim that his 1993 indictment by a West Feliciana Parish grand jury was tainted by discrimination in the grand jury foreman selection process.

Woodfox — one of three prisoners known as the “Angola Three” — has long maintained his innocence in Miller’s death. Human rights activists say the case against Woodfox is flawed. And they question whether the case was prosecuted because of Woodfox’s political activism.