In her two opinions since joining the U.S. Supreme Court, Justice Ketanji Brown Jackson, with a likely ally in Justice Sonia Sotomayor, appears to have signaled that problems in death penalty and other criminal cases are where she will raise her voice to hold her own and other courts accountable.

Jackson, joined by Sotomayor, issued her second written dissent in the capital case, Johnson v. Missouri, on Wednesday, a day after the justices denied review. Kevin Johnson, who was 19 when he killed a police officer whom he blamed for the death of his younger brother, was executed Tuesday night.