Foa said: “Lethal injection is designed to look like a clean, medical process. But lethal injection executions go wrong all the time. In Alabama, these have been demonstrably, miserably botched executions. Joe Nathan James Jr’s execution took three-and-a-half hours, prison officials repeatedly trying and failing to get access to a vein.”
That would unironically be more humane than a lethal injection. The injection was developed by non-doctors taking their best guess at what they thought would kill reliably and painlessly, but it's neither. And that's by necessity, no doctor would ever throw out their entire career by violating their oath as flagrantly as developing a substance with no purpose other than being poison.