Colin Dayan is Robert Penn Warren professor in the humanities at Vanderbilt University and the author of “The Law Is a White Dog: How Legal Rituals Make and Unmake Persons.”

We as a nation are guilty of the most horrific treatment of prisoners in the civilized world. In March, 400 prisoners in California’s Security Housing Units, as well as a number of prisoners’ rights organizations, petitioned the United Nations asking for help. Since then, the Center for Constitutional Rights has filed a federal lawsuit on behalf of prisoners at California’s Pelican Bay State Prison who have each spent between 10 and 28 years in solitary confinement . A class-action suit in Arizona challenges inadequate medical and mental health care that subjects prisoners to injury, amputation, disfigurement and death — especially in prolonged solitary confinement.

Supermax detention is the harshest weapon in the U.S. punitive armory. Once, solitary confinement affected few prisoners for relatively short periods. Today, most prisoners can expect to face solitary, for longer periods and under conditions that make old-time solitary seem almost attractive. The contemporary state-of-the-art supermax is a clean, well-lighted place. There is no decay or dirt. And there is often no way out.

This is not the “hole” portrayed in movies. As a sign of professionalism and advanced technology, extreme isolation and sensory deprivation constitute the “treatment” in these units. Supermaxes modify inmates’ spatial and temporal framework, severely damaging their sense of themselves: a terrible violence against the spirit and a betrayal of our constitutional and moral responsibilities.

More than a decade ago, I began visiting the “Special Management Units” at the Arizona State Prison Complex-Eyman in Florence. I completed a series of interviews in an attempt to understand this new version of solitary confinement. Prisoners there are locked alone in their cells for 23 hours a day. Their food is delivered through a slot in the door of their 80-square-foot cell. They stare at unpainted concrete walls onto which nothing can be put. They look through doors of perforated steel, what one officer described to me as “irregular-shaped Swiss cheese.” Except for the occasional touch of a guard’s hand as they are handcuffed and chained when they leave their cells, they have no contact with another human being.

In this condition of enforced idleness, prisoners are not eligible for vocational programs. They have no educational opportunities; books and newspapers are severely limited; post and telephone communication virtually nonexistent. Locked in their cells for as many as 161 of the 168 hours in a week, they spend most of the brief time out of their cells in shackles, with perhaps as much as eight minutes to shower. An empty exercise room — a high-walled cage with a mesh screening overhead, also known as the “dog pen” — is available for “recreation.”

These are locales for perpetual incapacitation, where obligations to society, the duties of husband, father or lover are no longer recognized. An inmate wrote me, “People go crazy here in lockdown. People who weren’t violent become violent and do strange things. This is a city within a city, another world inside of a larger one where people could care less about what goes on in here. This is an alternate world of hate, pain, and mistreatment.”

Situated on 40 acres of desert, Special Management Unit 2 is surrounded by two rings of 20-foot-high fence topped with razor wire, like a nuclear-waste storage facility. During my visits, I learned that those who have not violated prison rules — often jailhouse lawyers or political activists — are placed apart from other prisoners, sometimes for what is claimed to be their own protection; sometimes for what is alleged to be the administrative convenience of prison officials; sometimes for baseless, unproven and generally unprovable claims of gang membership.

We citizens are proud of our history. We are a nation of laws. But what kind of laws? Laws that permit solitary confinement, with cell doors, unit doors and shower doors operated remotely from a control center, with severely limited and often abusive physical contact. Has society’s current attention to the death penalty allowed us to forget the gradual destruction of mind and loss of personal dignity in solitary confinement, including such symptoms as hallucinations, paranoia and delusions?

The philosopher Jeremy Bentham came to believe that solitude was “torture in effect.” Other 19th-century observers, including Charles Dickens and Alexis de Tocqueville, used images of premature burial, the tomb and the shroud to represent the death-in-life of solitary confinement. Some 25,000 inmates are languishing in long-term isolation in America’s supermax prisons, with as many as 80,000 more in solitary confinement in other facilities.

A Senate Judiciary Committee panel heard testimony last month on solitary confinement. I hope that someone reminded lawmakers of Justice William Douglas’s words nearly 40 years ago: “Prisoners are still ‘persons.’ ”