Blind Injustice: A Former Prosecutor Exposes the Psychology and Politics of Wrongful Convictions. By Mark Godsey. University of California Press; 264 pages; $29.95 and £24.95.

Inside Private Prisons: An American Dilemma in the Age of Mass Incarceration. By Lauren-Brooke Eisen. Columbia University Press; 336 pages; $32. To be published in Britain in January; £26.95.

NO COUNTRY imprisons a larger share of its people than America. Its incarceration rate—693 of every 100,000—is nearly five times Britain’s, six times Canada’s and 15 times Japan’s. And that rate masks huge variations: Washington, DC, Louisiana and Georgia each lock up more than one in every 100 residents. Why?

“Blind Injustice” tries to answer that complex question from an unusual perspective. The author, Mark Godsey, used to be a federal prosecutor in New York. He went on to co-found the Ohio Innocence Project, which works to free the wrongly convicted. His book is about how his career change also changed his outlook, by showing up “problems in the system that I, as a prosecutor, should have seen, but about which I had simply been in denial”.

And it is about the police and prosecutors who uphold that system—the “normal, regular people…who would help an old man cross the road, or who would shovel the snow from a sick neighbour’s driveway, [but who] go back to their offices and commit acts of heartbreaking, callous injustice…because they are operating under a bureaucratic fog of denial.” Each of Mr Godsey’s six central chapters centres on a different systemic flaw: denial, ambition, bias, memory, intuition and tunnel vision.

People in all fields, of course, commit these deeply human sins. Tunnel vision, conformity born of a desire to please bosses and not to rock the boat, answering difficult questions not by trying to work out the right answer but by determining what is best for your team: such behaviour is not unique to America’s criminal-justice system. But for police and prosecutors, it can deprive people of their liberty and lives. Last month, for instance, Wilbert Jones left a prison in Baton Rouge, Louisiana, after almost 46 years. A judge threw out his conviction for rape because the prosecution failed to turn over to the defence evidence that might have helped his case (the state is appealing). Mr Jones entered prison at 19; he is now 65.

Mr Godsey’s work is memorable because he is able to show precisely how these flaws work in action. He describes prosecutors routinely denying requests to give inmates DNA tests, even though these could help free them. Prosecutors think of themselves as the good guys and, therefore, their opponents as bad. This leads to routine dehumanisation, such as when prosecutors in Chicago competed in a “two-ton contest” to see who could be the first to indict 4,000lb of human flesh (which led prosecutors to be especially hard on overweight defendants).

He is particularly—and with good reason—tough on elected judges, who know that being “tough on crime” will always win more votes than promises of sober fairness and probity; and on forensic science, a contributing factor in nearly half of all wrongful convictions (second only to false eyewitness accounts). He ends the book on a hopeful note, though. States across the country are implementing some of the changes he recommends. These include recording interrogations, standardising eyewitness-identification procedures, expanding access to post-conviction DNA testing and, perhaps most important, opening conviction-review boards inside prosecutors’ offices, to investigate post-conviction claims of innocence.

If Mr Godsey focuses on how people are unjustly jailed, Lauren-Brooke Eisen, a former lawyer now at New York University, has written a deeply researched, scrupulously fair book about private prisons, which house 126,000 people in America, or 7% of state inmates and almost 18% of federal prisoners. They are opaque in a way that state prisons are not; despite the book’s title, Ms Eisen barely manages to get inside a private prison.

Some liberals cast private prisons as a driver of mass incarceration. Their business model is built around it and, as Ms Eisen notes, they have lobbied for policies that have helped them. Some feel that profiting from other people’s incarceration is inherently immoral, or that it violates constitutional protections against involuntary servitude and cruel and unusual punishment.

But Ms Eisen convincingly argues that they are a symptom, rather than a cause, of America’s over-punitive, carceral state. Private prisons took off because governments could not build prisons quickly enough to hold all the people they sentenced. Now private-prison firms are diversifying with the times by building treatment centres and electronic-monitoring services as America’s justice system explores alternatives to imprisonment. Some may find it depressing that these firms are simply looking for another way to profit from society’s unfortunates. But it also shows that these companies respond to political demand, and that the best way to do away with private prisons is to lock up fewer people.