(CNN) -- Gov. Bill Haslam on Thursday signed a bill allowing Tennessee to electrocute death row inmates when the state is unable to obtain lethal injection drugs.
Controversy over lethal injections has been brewing in recent years after European manufacturers, including the Denmark-based manufacturer of pentobarbital, banned U.S. prisons from using their drugs in executions.
In 2009, the U.S.-based manufacturer of sodium thiopental, a drug also commonly used in executions, stopped making the painkiller.
Many states have scrambled to find products from overseas or have used American-based compounding pharmacies to create substitutes.