A prison is a trap for catching time. Good reporting appears often about the inner life of the American prison, but the catch is that American prison life is mostly undramatic—the reported stories fail to grab us, because, for the most part, nothing happens. One day in the life of Ivan Denisovich is all you need to know about Ivan Denisovich, because the idea that anyone could live for a minute in such circumstances seems impossible; one day in the life of an American prison means much less, because the force of it is that one day typically stretches out for decades. It isn’t the horror of the time at hand but the unimaginable sameness of the time ahead that makes prisons unendurable for their inmates. The inmates on death row in Texas are called men in “timeless time,” because they alone aren’t serving time: they aren’t waiting out five years or a decade or a lifetime. The basic reality of American prisons is not that of the lock and key but that of the lock and clock.

That’s why no one who has been inside a prison, if only for a day, can ever forget the feeling. Time stops. A note of attenuated panic, of watchful paranoia—anxiety and boredom and fear mixed into a kind of enveloping fog, covering the guards as much as the guarded. “Sometimes I think this whole world is one big prison yard, / Some of us are prisoners, some of us are guards,” Dylan sings, and while it isn’t strictly true—just ask the prisoners—it contains a truth: the guards are doing time, too. As a smart man once wrote after being locked up, the thing about jail is that there are bars on the windows and they won’t let you out. This simple truth governs all the others. What prisoners try to convey to the free is how the presence of time as something being done to you, instead of something you do things with, alters the mind at every moment. For American prisoners, huge numbers of whom are serving sentences much longer than those given for similar crimes anywhere else in the civilized world—Texas alone has sentenced more than four hundred teen-agers to life imprisonment—time becomes in every sense this thing you serve.

For most privileged, professional people, the experience of confinement is a mere brush, encountered after a kid’s arrest, say. For a great many poor people in America, particularly poor black men, prison is a destination that braids through an ordinary life, much as high school and college do for rich white ones. More than half of all black men without a high-school diploma go to prison at some time in their lives. Mass incarceration on a scale almost unexampled in human history is a fundamental fact of our country today—perhaps the fundamental fact, as slavery was the fundamental fact of 1850. In truth, there are more black men in the grip of the criminal-justice system—in prison, on probation, or on parole—than were in slavery then. Over all, there are now more people under “correctional supervision” in America—more than six million—than were in the Gulag Archipelago under Stalin at its height. That city of the confined and the controlled, Lockuptown, is now the second largest in the United States.

The accelerating rate of incarceration over the past few decades is just as startling as the number of people jailed: in 1980, there were about two hundred and twenty people incarcerated for every hundred thousand Americans; by 2010, the number had more than tripled, to seven hundred and thirty-one. No other country even approaches that. In the past two decades, the money that states spend on prisons has risen at six times the rate of spending on higher education. Ours is, bottom to top, a “carceral state,” in the flat verdict of Conrad Black, the former conservative press lord and newly minted reformer, who right now finds himself imprisoned in Florida, thereby adding a new twist to an old joke: A conservative is a liberal who’s been mugged; a liberal is a conservative who’s been indicted; and a passionate prison reformer is a conservative who’s in one.

The scale and the brutality of our prisons are the moral scandal of American life. Every day, at least fifty thousand men—a full house at Yankee Stadium—wake in solitary confinement, often in “supermax” prisons or prison wings, in which men are locked in small cells, where they see no one, cannot freely read and write, and are allowed out just once a day for an hour’s solo “exercise.” (Lock yourself in your bathroom and then imagine you have to stay there for the next ten years, and you will have some sense of the experience.) Prison rape is so endemic—more than seventy thousand prisoners are raped each year—that it is routinely held out as a threat, part of the punishment to be expected. The subject is standard fodder for comedy, and an uncoöperative suspect being threatened with rape in prison is now represented, every night on television, as an ordinary and rather lovable bit of policing. The normalization of prison rape—like eighteenth-century japery about watching men struggle as they die on the gallows—will surely strike our descendants as chillingly sadistic, incomprehensible on the part of people who thought themselves civilized. Though we avoid looking directly at prisons, they seep obliquely into our fashions and manners. Wealthy white teen-agers in baggy jeans and laceless shoes and multiple tattoos show, unconsciously, the reality of incarceration that acts as a hidden foundation for the country.

How did we get here? How is it that our civilization, which rejects hanging and flogging and disembowelling, came to believe that caging vast numbers of people for decades is an acceptably humane sanction? There’s a fairly large recent scholarly literature on the history and sociology of crime and punishment, and it tends to trace the American zeal for punishment back to the nineteenth century, apportioning blame in two directions. There’s an essentially Northern explanation, focussing on the inheritance of the notorious Eastern State Penitentiary, in Philadelphia, and its “reformist” tradition; and a Southern explanation, which sees the prison system as essentially a slave plantation continued by other means. Robert Perkinson, the author of the Southern revisionist tract “Texas Tough: The Rise of America’s Prison Empire,” traces two ancestral lines, “from the North, the birthplace of rehabilitative penology, to the South, the fountainhead of subjugationist discipline.” In other words, there’s the scientific taste for reducing men to numbers and the slave owners’ urge to reduce blacks to brutes.

William J. Stuntz, a professor at Harvard Law School who died shortly before his masterwork, “The Collapse of American Criminal Justice,” was published, last fall, is the most forceful advocate for the view that the scandal of our prisons derives from the Enlightenment-era, “procedural” nature of American justice. He runs through the immediate causes of the incarceration epidemic: the growth of post-Rockefeller drug laws, which punished minor drug offenses with major prison time; “zero tolerance” policing, which added to the group; mandatory-sentencing laws, which prevented judges from exercising judgment. But his search for the ultimate cause leads deeper, all the way to the Bill of Rights. In a society where Constitution worship is still a requisite on right and left alike, Stuntz startlingly suggests that the Bill of Rights is a terrible document with which to start a justice system—much inferior to the exactly contemporary French Declaration of the Rights of Man, which Jefferson, he points out, may have helped shape while his protégé Madison was writing ours.