Joe Biden supported capital punishment unvaryingly over his 36-year Senate career. He helped enact legislation that expanded the practice. As veep, he served a president who (on paper) backed the death penalty, and not only for homicide. Still, because of Biden, the current spate of federal death sentences consummated under President Trump will be the last for years at least. Now publicly against the death penalty, the president-elect has done a glaring turnabout, albeit in lockstep with America’s governing class. The total of all executions in 2020, state and federal, is 17—lower than any yearly sum in almost three decades,...