American conservatism rose hand-in-hand with the growth of mass incarceration. For decades, conservatives deployed "tough on crime" rhetoric to attack liberals as out-of-touch elitists who coddled criminals while the nation spiraled toward disorder. As a result, conservatives have been the motive force in building our vast prison system. Indeed, expanding the number of Americans under lock and key was long a point of pride for politicians on the right - even as the U.S. prison population eclipsed international records.

Over the last few years, conservatives in Washington, D.C. and in...