Deterrence is at the heart of the criminal-justice enterprise. Criminal sanctions are intended ﬁll a number of functions-to punish, to fulﬁll justice, to express the public’s standards and priorities, to incapacitate-but they are centrally designed to control: to shape, through the prospect of unpleasantness of various kinds, the behavior of oﬀenders and potential oﬀenders. Deterrence is particularly at the heart of the preventive aspiration of criminal justice. It is not the only such route; various facilitative and rehabilitative measures, such as job training through probation and drug treatment in prison, also hold out this hope. But deterrence, whether through preventive patrol by police oﬃcers or mandatory federal prison sentences for ﬁrearms oﬀenders, is the principal mechanism through which the central feature of criminal justice, the exercise of state authority, works-it is hoped-to diminish oﬀending and enhance public safety. The framework for deterrence is simple and familiar. Oﬀenders and
potential oﬀenders, like other people, seek reward and seek to avoid loss. If particular acts carry penalties, then those acts will become less attractive. The stiﬀer, quicker and more reliable the penalty, the less attractive the act will be. This is, openly and frankly, the business of the socially sanctioned threat. There is a threatener; there is a proscribed act; there is a threat associated with that act; there is an audience for that threat. Get it right and the act is not carried out, or, at least, is carried out less often. A great deal of scholarly attention has been devoted to the theory and
practice of deterrence. It has focused on oﬀenders and the central question of their rationality, on their perceptions of the risks they face and whether those risks inﬂuence their behavior. It has focused on particular sanctions and their eﬃcacy. It has focused on the actual behavior of criminal-justice authorities, and on how that behavior is interpreted by oﬀenders. The resulting literature is rich and diverse. This book seeks to build on and expand that literature. It has its intellec-
tual origins, in part, in concrete ﬁeld experience-actual attempts to prevent and control crime. It is not an account of, or an evaluation of, those eﬀorts: This is a work of theory, or at any rate aspires to be, and theory cannot rest entirely on any example or narrow set of examples. If we judge that the death penalty deters homicide, that does not mean that all attempts to produce
deterrence work, or that the general ideas through which we understand and pursue deterrence are correct. If we judge that it does not, neither does that prove that deterrence does not operate in other cases, or that the general ideas through which we consider deterrence are wrong, or that the death penalty handled diﬀerently might deter. The work that provoked the explorations in this book is not a suﬃcient basis on which to ground those explorations; the explorations, in turn, go well beyond the work. So this is not a book about that work. At the same time, it may be useful to sketch that work and the initial questions it raised, at least in my mind, for deterrence theory, questions I hope this book will help address. The work emerged from an attempt to address juvenile gun violence,
which at the time was epidemic in the USA, through problem-oriented policing.1 My colleagues at the Kennedy School of Government at Harvard University, Anne Piehl and Anthony Braga, and I set up in 1995 with a group of extraordinary practitioners in Boston: oﬃcers from the Boston Police Department’s Youth Violence Strike Force, or gang unit; probation oﬃcers from Dorchester District Court; prosecutors from the district attorney and US Attorney’s oﬃces; fugitive apprehension oﬃcers from the Massachusetts Department of Youth Services; special agents from the Boston oﬃce of the Bureau of Alcohol, Tobacco, and Firearms; gang outreach workers attached to the city’s Streetworker Program. They taught us that the gun-violence problem was almost entirely one of friction within and between small drug crews: “gangs,” as our Boston partners called them. I, at least, resisted what they knew. I was focused on much broader issues:
gun availability and use, community-wide violence dynamics, that sort of thing. But they were entirely correct. Some sixty-one crews with something like 1,300 members were killing each other along quite clearly identiﬁable lines of rivalry and alliance. Most of the violence was personal-respect, boy/girl, Hatﬁeld-and-McCoy vendetta-rather than about the drug business. Participants in the street action were extraordinarily active oﬀenders; three-quarters of both homicide victims and perpetrators had criminal records and averaged nearly ten prior arrests apiece across a wide range of crimes: drug-dealing, drug use, disorder oﬀenses, weapons, and more. Fully a quarter of known homicide oﬀenders were on active probation status at the time they killed. And the issue we had entered focusing upon was mistaken: Juvenile gun violence was a relatively small part of the real problem, which involved young minority men up to, roughly, age twenty-ﬁve. Our practitioner partners also showed us a commonsense but extremely
unusual approach that they had used very successfully a number of times to stop the violence of particular drug crews at particular times: They lowered the boom on all crimes every member of the group was committing, while simultaneously telling them that the crackdown would stop when the shooting did and oﬀering them social services of various kinds. Together we built that approach into something designed to stop the violence of all Boston’s drug crews.