Did the Ninth Circuit err in holding that Arizona did not violate the Ex Post Facto Clause by sentencing Mr. McGill to death under the later-enacted statute simply because that statute could be characterized as 'procedural'?

QUESTION PRESENTED The Ex Post Facto Clause prohibits retroactive increases in criminal punishment. When Mr. McGill committed the crime for which he was convicted, Arizona law did not allow the State to sentence him to death. Instead, the State sentenced him to death under a provision enacted after the crime occurred. Did the Ninth Circuit err in holding that Arizona did not violate the Ex Post Facto Clause by sentencing Mr. McGill to death under the later-enacted statute simply because that statute could be characterized as “procedural?”