A recent page-one article in The New York Times raised fascinating questions about what other jurisdictions can learn from New York City, where the police force expanded in the 1990s and both crime and incarceration have decreased since then. CBKB staff often field questions about whether the benefits of hiring more police officers outweigh the costs. Like so many issues involving criminal justice spending, determining what will deliver the biggest return on investment is complex—and the answers aren’t limited to law enforcement and prison, but extend to education, employment, and other proven interventions. But in this case, the answer hinges on what, exactly, additional police officers will do, and how will they do it?

In 2011, Steven Durlauf and Daniel Nagin published an article in Criminology & Public Policy, recommending a shift in resources from corrections to law enforcement, including “a more effective use of police.” In the same issue of the journal, Mark Bergstrom, executive director of the Pennsylvania Commission on Sentencing, wrote an essay in response, and cautioned that “an increase in law enforcement…without clear deployment standards could contribute to an increase in prison admissions.” As he explained in a blog post for CBKB, “With drug offenses, for instance, although increased police visibility may suppress or deter crime, increased police enforcement may increase arrests,” which could in turn increase court caseloads and incarceration. Bergstrom wrote that Durlauf and Nagin’s proposal “has important implications for the criminal justice system,” though he also spelled out critical budgetary questions: “How would savings be recaptured and transferred? What entity would coordinate criminal justice financing across different levels of government?”

Others maintain that police should focus on improving their legitimacy—their standing in the community—more than their possible role in deterring criminal behavior. In speaking about this at the National Institute of Justice in 2010, Yale Law School Professor Tracey Meares said that “law enforcers are not availing themselves of the potential of legitimacy,” which can help them fight crime. She said that when “good treatment and fairness” are present, people “are more likely to voluntarily obey the law.” Police stops, she noted, “can be costly, even when they are lawful and constitutional.”

In 2010, George Gascón, a former chief of police in Mesa, Arizona, and San Francisco, where he is now district attorney, and Todd Foglesong, a senior research associate at the Harvard Kennedy School, published a paper in which they recommended assigning values “to aspects of police work that are poorly measured or not quantified as benefits,” including fairness, professional competence, and quality of service, as well as “diffusing social tension and preventing the escalation of interracial conflicts,” all of which can contribute to legitimacy. They concluded, “Police departments today have to develop a new and different kind of bottom line, one that resonates with the communities most in need of safety and justice.”

These intangible benefits and costs have enormous policy implications. If other jurisdictions were to adopt the New York Police Department’s “stop and frisk” policy, for example, they might import the controversy that accompanies it. As Jens Ludwig of the University of Chicago Crime Lab told the Times, it is unclear “whether or not stop-and-frisk is worth the costs that the practice imposes on society. But there’s a complicated trade-off here that needs to be acknowledged.” Any law enforcement agency seeking to weigh a program’s costs and benefits comprehensively would need to establish a detailed plan about deployment and activities, as well as a plan for evaluating them.

This post also appears on the blog of the Cost-Benefit Knowledge Bank for Criminal Justice, which is a project of the Vera Institute of Justice.