Death row inmates are suing to stop the importation of a drug used in executions.
Attorneys for the prisoners in Tennessee, Arizona and California argued before U.S. District Judge Richard Leon on Thursday that the Food and Drug Administration is breaking the law by allowing sodium thiopental to be imported since it is an unapproved drug manufactured overseas.
The Obama administration argues it has discretion to allow unapproved drugs into the U.S. and wants Leon to dismiss the case.
The drug's U.S. manufacturer announced last year that it would no longer produce it, forcing corrections officials to delay many executions. Many of the nation's 34 death penalty states switched to an alternative drug, pentobarbital.
Both drugs are anesthetics used to put inmates to sleep before other lethal drugs are administered.