If anyone still thinks American criminal justice is a matter of jury trials, constitutional rights, and adversarial justice, this book should disabuse them of all that. The reality is that millions of defendants—largely indigent, minimally represented people of color—acquiesce to plea deals proffered by busy prosecutors with little time for individualized justice. And although copping a plea enables defendants to avoid the delay and increased penalties they risk if they go to trial, their punishments are markedly more severe than those imposed in Canada or Europe and much higher than in the United States 40 years ago. Mass incarceration is the name we give to the cumulative result.

Prosecutors have always been key players in criminal justice, especially in America, where their powers are subject to little oversight. But today their control of case outcomes is unmatched and largely unchecked. Prosecutors bring charges, propose bail, shape plea deals, and specify penalties with little effective resistance from defense attorneys, grand juries, or judges. The district attorney’s office has become the nerve center of the penal state, the place where the ideals of American justice are translated into the realpolitik of penal control. While prosecutors are supposed to play a dual role—advocates for “the people” as well as impartial ministers of justice—for as long as anyone can remember, all the political pressure has pushed toward the former.

This shift in the balance of power has been under way ever since America became a high-crime society in the late 1960s. The move away from rehabilitation, the spread of mandatory penalties, the creation of new categories of crime, and the priority given to public safety over offenders’ rights—these all increased prosecutors’ leverage and incentivized them to use it aggressively. American sentencing was once a multistep process, involving prosecutors, judges, juries, parole boards, and prison administrators. Today, prosecutors have become the dominant actors, disposing of cases with the stroke of a pen.

Prosecutors do their work behind closed doors, with little public accountability other than to grand juries (who are little more than rubber stamps) and periodic elections (that are mostly uncontested). And they have discretionary power to bring any charges that the law allows and the facts support. Given the interpretive latitude enabled by our duplicative criminal-law codes, any wrongful act can give rise to multiple charges and penalties of varying seriousness. In New York, shoplifters can be charged with misdemeanor theft, felony theft, or even burglary (if they were previously barred from the store, or reached behind the counter without permission), exposing them to punishments ranging from a few months’ probation to seven years in prison. A burglary that involves no actual violence can be charged as a violent felony carrying a mandatory minimum prison sentence of 42 months (and a 15-year maximum) on the theory that the burglar might have encountered someone inside. This loose relation between wrongful acts and criminal charges allows prosecutors to pile on charges and negotiate from positions of strength. Is it any wonder that between 95 percent and 98 percent of convictions result from guilty pleas?

Mass incarceration was never a planned policy goal or an articulated strategy. It is, instead, the cumulative result of four decades of tough-on-crime laws and practices adopted all across the nation: a long-term buildup that has left America with the world’s highest rate of incarceration, largely targeted on lower-class blacks and Latinos. Given the many moving parts that produced this outcome, there is much blame to go around and critics have pinned responsibility on everyone from Nixon and Reagan to Bill and Hillary. Some even blame Lyndon Johnson for abandoning social-policy programs in the face of conservative opposition and for increasing federal funding for law enforcement. More-balanced accounts point to public concern about criminal violence, including in minority communities where the body count was worst, and to America’s tendency to deal with social problems using penal controls rather than welfare provision.