The European Union, the Drug Enforcement Administration, and American prison officials are locked in an unusual battle over sodium thiopental, a drug used for lethal injections in most state executions.

The dispute began in 2008, when the EU called for worldwide abolition of the death penalty. Since that declaration, the U.K., Germany, and other countries have erected regulatory barriers to prevent pharmaceutical companies from exporting sodium thiopental to the United States. Hospira, the only remaining U.S. manufacturer of the drug, announced in January that it would stop making it after Italy nixed the company’s plans to open a manufacturing plant there.

As a result, states have been running out of sodium thiopental. But since there are still executions to be carried out, many states began doing what everyone else does when government policy makes it difficult to legally obtain the drugs they want: They started buying the stuff on the black market. William Montross, an attorney with the Southern Center for Human Rights in Atlanta, told NPR in March that Georgia was illegally purchasing the drug from a company that operated out of the back of a driving school in London. According to various media reports, California, Arkansas, Tennessee, and Kentucky also have obtained the drug illegally.

Enter the Drug Enforcement Administration (DEA). In March the agency seized supplies of sodium thiopental from prison officials in Georgia. Days later, the DEA confiscated the drug from corrections officials in Kentucky and Tennessee. Ohio, Oklahoma, and Texas, meanwhile, have said they will switch to pentobarbital, a drug commonly used to euthanize pets.