On July 8 of last year, a 50-year-old man named Todd Ashker, an inmate at California’s Pelican Bay State Prison, began a hunger strike. He had compiled a list of demands, but the essential one was that the policy that dictated the terms of his imprisonment be abolished. Ashker was housed in Pelican Bay’s Security Housing Unit, the most restrictive prison unit in California and a place of extreme isolation. Convicts stay in their cells 23 hours a day and leave only to exercise in a concrete room, alone; their meals are fed into their cell through a slot. Other than an awareness that they are staring at the same blank wall as seven other men kept in their “pod,” they are completely alone. Ashker has been there since 1990; in his view, he has been subject to nearly a quarter-century of continuous torture. “I have not had a normal face-to-face conversation with another human being in 23 years,” he told me recently, speaking from the other side of a thick plate of glass.