COLUMBIA, Mo. (AP) — A Missouri death row inmate who says execution drugs could interact with his medical condition is asking the U.S. Supreme Court to intervene.

Ernest Lee Johnson is arguing that a brain tumor removed by surgeons could cause seizures and severe pain in reaction to Missouri’s execution drug.

Johnson was sentenced to death for killing three Casey’s General Store workers during a Columbia robbery in 1994.

Johnson’s appeal is moving through lower courts. But Johnson wants the U.S. Supreme Court to intervene because the high court is currently considering a similar case of another Missouri death row inmate with a rare medical condition that causes blood-filled tumors.

Both argue complications with their conditions and the execution drug could lead to cruel and unusual punishment.