For nearly 40 years the United States has been gripped by policies that have placed more than 2.5 million Americans in jails and prisons designed to hold a fraction of that number of inmates. Our prisons are not only vast and overcrowded, they are degrading. Mass Incarceration on Trial examines a series of landmark decisions about prison conditions that has opened an unexpected escape route from this trap of 'tough on crime' politics. This set of rulings points toward values that could restore legitimate order to American prisons and lead to the end of mass incarceration.