A U.S. Supreme Court argument Wednesday over a lethal injection drug used by Oklahoma quickly developed into a sometimes bitter contest between the court’s liberal and conservative wings over the death penalty.

“Let’s be honest about what’s going on here,” Justice Samuel Alito Jr. said to Robin Konrad, counsel to death row inmate Richard Glossip. “Is it appropriate for the judiciary to countenance what amounts to a guerilla war against the death penalty which consists of efforts to make it impossible for the states to obtain drugs that could be used to carry out capital punishment with little, if any, pain? And so the states are reduced to using drugs like this one, which give rise to disputes about whether, in fact, every possibility of pain is eliminated.”