WASHINGTON — The Supreme Court on Monday rejected Alabama’s bid to execute a death row inmate by lethal injection, leaving in place a lower court ruling that his preference for lethal gas is a viable alternative method.

Kenneth Smith, sentenced to death for murdering Elizabeth Sennett in 1988, objected to being executed by lethal injection because of the pain it would cause. He alleged it would violate his right to be free of cruel and unusual punishment under the Eighth Amendment to the Constitution.