Winfield would have been killed with an intravenous dose of the drug pentobarbital, which Missouri adopted as its go-to lethal injection drug last year. This came as states across the country were struggling to find the drugs for lethal injections, which has caused officials in some of these states to contemplate bringing back other methods of execution such the gas chamber or firing squad.
Winfield’s attorneys had also filed other appeals, including one that criticized the secrecy surrounding the state’s lethal injection process. This secrecy has been the source of considerable criticism. Several media organizations, including the Associated Press and the Guardian, filed a lawsuit last month to try to get Missouri to release more information about where the state is getting the drugs.
The state has executed four people in 2014, the same number of executions it carried out between 2006 and 2013.