SUPPORT FOR LEGALIZING marijuana is surging among the public, as the position moves closer to the mainstream of the Democratic Party. This week, Senate Minority Leader Chuck Schumer, D-N.Y., a politician adept at reading and responding to the public mood, introduced a bill to decriminalize cannabis at the federal level. And in some states, pot is already being taxed and regulated.

Underneath that progress, however, a war is still raging. New data published here for the first time show that in at least 21 states, more people were arrested in 2016 than in 2014. Meanwhile, thousands of people who were arrested previously for what is now legal in many places continue to languish in prisons.

Fate Winslow is one of them. Crammed in a dorm with more than 80 other prisoners at the Louisiana State Penitentiary in Angola, he is serving out a life sentence. “Now pack[ed] in like sardines,” he wrote in a recent letter from the prison. They’re double-bunked and there’s no air conditioning to fight the Louisiana heat. “How is it fit to get 86 bodies no air?” he wondered. “Well you see the picture — very hot.”

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