WASHINGTON (AP) — Hearing his first arguments in a death penalty case, Supreme Court Justice Brett Kavanaugh seemed open Tuesday to the arguments of a Missouri inmate who says his rare medical condition could result in severe pain if he is executed by lethal injection.

The court’s newest justice could hold the key vote in Russell Bucklew’s case. That’s because his eight colleagues split 4 to 4 earlier this year over whether to allow Bucklew’s execution to proceed. Justice Anthony Kennedy provided the fifth vote to spare Bucklew. Kavanaugh replaced Kennedy, who retired in July.

Bucklew, on death row for a 1996 murder, has said that a tumor in his throat is likely to burst during the lethal injection procedure, causing him to choke on his own blood. Bucklew argues that subjecting him to lethal injection would violate the Constitution’s ban on cruel and unusual punishment.

Among the questions Kavanaugh wanted answered was whether Bucklew would be lying flat during the execution, which Bucklew’s attorneys have said would be problematic. Kavanaugh, who heard no death penalty cases in his 12 years as an appeals court judge, also asked whether there’s any legal limit on pain associated with an execution. The justice also aimed all his questions at the lawyer representing Missouri, which can be a sign at the Supreme Court that a justice is inclined to vote for the other side.

“Are you saying even if the method creates gruesome and brutal pain you can still do it because there’s no alternative?” Kavanaugh at one point asked Missouri’s attorney, D. John Sauer. He later asked Sauer: “Your opposing counsel said, even if everything goes according to plan, there will still be significant suffering. Can you respond to that?”