The U.S. Supreme Court rejected a Missouri death row inmate’s petition to be executed via firing squad instead of lethal injection after he argued that lethal injection would cause him significant pain due to his medical condition. The inmate, Ernest Lee Johnson, argued that lethal injection might trigger an epileptic seizure that would cause severe pain. He had sought an alternative method of execution instead of receiving a deadly dose of pentobarbital, which can cause seizures, according to studies. Johnson, whose epilepsy is caused by a brain tumor, was sentenced to death for three murders he committed in 1994 during a gas station robbery. His lawyers had argued that lethal injection would violate the Eighth Amendment, which prohibits the government from imposing cruel and unusual punishments, and excessive bail. But Johnson’s bid was rejected by the high court in an unsigned order (pdf) on Monday. Liberal-leaning Justice Sonya Sotomayor dissented and was joined …