Judge Learned Hand called “the ghost of the innocent man convicted” an “unreal dream.” But in “Convicting the Innocent,” Brandon L. Garrett shows that it can be a “nightmarish reality.” Since the late 1980s, DNA testing has exonerated more than 250 wrongly convicted people, who spent an average of 13 years in prison for crimes they didn’t commit. (There is every reason to think that more people have been wrongly convicted since then, but only these 250 have been definitively exonerated by postconviction DNA tests.) Seventeen of the 250 were sentenced to die, and 80 to spend the rest of their lives in prison. By poring over trial transcripts and interviewing lawyers, prosecutors and court reporters, Garrett, a law professor at the University of Virginia School of Law, seeks to explore who these 250 innocent people are, and why they were wrongly convicted. His alarming conclusion: the wrongful convictions were not idiosyncratic but resulted from a series of flawed practices that the courts rely on every day, namely, false and coerced confessions, questionable eyewitness procedures, invalid forensic testimony and corrupt statements by jailhouse informers. Garrett’s book is a gripping contribution to the literature of injustice, along with a galvanizing call for reform.

Almost 90 percent of the 250 innocent people later exonerated were falsely convicted of rape, or rape and murder, and 40 of them actually confessed to crimes they didn’t commit, most adding specific details that only the real culprit could have known. How did this happen?

Garrett describes how the police, intentionally or not, fed details of the crime to the suspects — and then recorded only portions of the interrogations so that it was difficult for defense lawyers and jurors to reconstruct the truth. Even the selectively recorded interrogations make for painful reading, as the suspects offer facts that are inconsistent with what happened, and the police browbeat them into false confessions. (Detective: “You hung her!” Vasquez: “O.K., so I hung her.”) Unfortunately, the Supreme Court has refused to focus on whether confessions are reliable, asking instead whether they were coerced, or offered without Miranda warnings. Garrett says the best protection against false confessions would be to require that police record interrogations from beginning to end; at the moment, 11 states and the District of Columbia are required or encouraged to record at least some interrogations.