On Feb. 14, 2018, Nikolas Cruz took an AR-15 semiautomatic rifle to the Marjorie Stoneham Douglas High School in Parkland, Florida where he murdered 17 people and wounded 17 others. This horrific crime was one of the deadliest school shootings in American history. If ever there was a living embodiment of what some death penalty supporters call the “worst of the worst,” a poster boy for the supposed necessity of capital punishment, Nikolas Cruz seemed to be it. Yet Thursday a jury of seven men and five women, drawn from all walks of life, sentenced Cruz to life in prison...