The U.S. Supreme Court has stayed the execution of a Missouri death row prisoner who was set to become the first to be executed since Oklahoma’s botched killing last month. Russell Bucklew’s attorneys asked for a stay because he suffers from a medical condition they say could cause him undue suffering. Bucklew won an initial stay on Tuesday, and the Supreme Court followed up on Wednesday with another ruling halting the execution and sending the case back to a federal appeals court. The court’s ruling marked a shift from a pattern of rejecting similar cases, suggesting justices may be concerned about the secretive and unregulated compounding pharmacies that provide the lethal injection drugs states like Missouri refuse to disclose.