In 2015, New York announced it had reached a landmark settlement with the New York Civil Liberties Union, which sued over the state's aggressive use of solitary confinement to discipline inmates. Five Mualimm-ak is one of the activists who pushed for the changes. He spent five years in solitary and says it left him broken. "When people say you survived solitary? Nobody survives that," he says. Gov. Andrew Cuomo, a Democrat, agreed to a multi-year process phasing in limits on the time inmates...

In January, Dylann Roof was sentenced to death for killing nine black churchgoers at a prayer meeting in Charleston, S.C. Since then, some commentators have debated whether Roof should have had the right to fire his attorneys when they wished to introduce evidence of mental illness — and whether, or when, mental illness should disqualify someone for capital punishment. Most Americans oppose the death penalty for the mentally ill, a category that ranges from mild to severe. But our research...