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Murders are spiking. Police should be part of the solution.

There’s solid evidence for the crime-fighting abilities of police. But it requires a close look.

A police officer standing on a street with houses in the background.
A police officer watches a crime scene on April 4, 2009, in Pittsburgh, Pennsylvania.
Ross Mantle/Getty Images

Last year, the US’s murder rate spiked by almost 30 percent. So far in 2021, murders are up nearly 10 percent in major cities. The 2020 increase alone is the largest percentage increase ever recorded in America — and a reversal from overall declines in murder rates since the 1990s.

American policymakers now want answers on this surge. One approach has good evidence behind it: the police.

There is solid evidence that more police officers and certain policing strategies reduce crime and violence. In a recent survey of criminal justice experts, a majority said increasing police budgets would improve public safety. The evidence is especially strong for strategies that home in on very specific problems, individuals, or groups that are causing a lot of crime or violence — approaches that would require restructuring how many police departments work today.

That runs contrary to the push to “defund the police” in progressive circles, which tend to focus on cutting policing to boost alternatives. In the same survey of experts, most said that increasing social service budgets would improve public safety. But experts also say there’s no reason, if the goal is to fight crime, that communities shouldn’t expand both policing and social services — what University of Missouri St. Louis criminologist Richard Rosenfeld calls a “both-and” approach.

One problem for a purely social services approach, which can range from job creation to better schools to mental health treatment, is it generally takes longer to work. Problems like poverty, education, and other underlying issues that contribute to crime can take years, or even decades, to truly address.

The impact of police, meanwhile, tends to happen quickly — almost immediately deterring and intercepting would-be criminals with the presence of officers. For policymakers looking for quick action, that’s an important distinction, suggesting that police have to play a role even if other social services are deployed for longer-term solutions.

“I know people don’t want to hear this, and I empathize with that,” Anna Harvey, a public safety expert at New York University, told me. “[But] as far as the research evidence goes, for short-term responses to increases in homicides, the evidence is strongest for the police-based solutions.”

Part of the explanation is that law enforcement approaches have generally received more research attention than the alternatives. This does not mean that the alternatives to policing don’t work. Some might prove to be even better than the police alone in certain circumstances, but they just haven’t been studied enough to show that yet.

Nor does the evidence suggest that policing approaches are without flaws. There are problems with the research here as well, including that it frequently fails to measure the unintended costs and consequences of policing, like the burden placed on communities of color disproportionately targeted and hassled by the police.

Every criminal justice expert I’ve spoken to has also said that more work needs to be done to hold police accountable — and the survey of experts found that most agreed more accountability would also improve public safety.

So the evidence doesn’t indicate that America should continue the punitive, unaccountable model of policing that’s dominated over the past few decades. To the contrary, much of the research supports changes to how policing is done to focus narrowly on problems, city blocks, and even individuals known to disproportionately contribute to crime — contrary to the dragnet approaches, like “stop-and-frisk,” that end up harassing entire communities.

In short, policing works to reduce crime and violence. But how policing is done can change — and change could even make policing more effective for crime-fighting while addressing some of the problems to which Black Lives Matter protests have called attention.

There’s good evidence police reduce crime and violence

A 2020 study published by the National Bureau of Economic Research concluded, “Each additional police officer abates approximately 0.1 homicides. In per capita terms, effects are twice as large for Black versus white victims.”

A 2005 study in the Journal of Law and Economics took advantage of surges in policing driven by terror alerts, finding that high-alert periods, when more officers were deployed, led to significantly less crime.

A 2016 study published in PLOS One looked at what happened when more New York City police officers were deployed in high-crime areas as part of an effort called “Operation Impact,” concluding these deployments were associated with less crime across the board.

The question, though, isn’t just whether police work to reduce crime, but how to deploy police to ensure that actually happens. There are proven ways, experts say, to make officers more effective than the traditional mode of policing in the US.

Hot spot policing, for example, focuses on problem areas, even down to specific city blocks, with disproportionate levels of crime and violence. Police departments send officers to these places with a goal of deterring further disorder. In some versions of this approach, police don’t even have to take action against people on the block, focusing on surveillance instead. The idea is that the mere presence of police should prevent people from committing crimes — a sort of scarecrow effect.

A 2019 review in the Journal of Experimental Criminology looked at dozens of studies and found hot spot policing reduced crime without merely displacing it to other areas, and, in fact, there was evidence of “diffusion” in which crime-fighting benefits actually spread to surrounding areas. The review relied on several strong studies, including randomized controlled trials (generally the gold standard of research), suggesting that the findings were based on solid ground.

Another approach, problem-oriented policing, homes in on a chronic issue — say, shootings in a community — and brings together local resources and agencies, beyond the police, to address that problem. This uses a “scanning, analysis, response, assessment” model, also known as “SARA,” that detects the problem, analyzes the solutions, executes a response, and evaluates those efforts to iterate on them. The goal is not just to treat the problem in the short term but hopefully cure it in the longer term. Depending on the specific problem and the ensuing analysis, police might play a major role or more of a supplementary one.

A 2020 review of the evidence from the Campbell Collaboration, which conducts policy research reviews, estimated that problem-oriented policing produces a nearly 34 percent reduction in crime and disorder relative to control groups. This was based on a few fairly strong studies, including randomized controlled trials — suggesting the research base here is, like hot spot policing, on strong footing.

One strategy that’s drawn a lot of media attention, including at Vox, is focused deterrence. With this strategy, police focus on specific individuals and organizations, particularly gangs, and deliver a clear message: You must stop engaging in violent or criminal activity, and the community will provide resources to make that easier, or the police will come down on you with serious charges. As part of this, the police tend to partner with other groups in and out of government to provide a carrot — job training, education, government benefits, and so on — to help people get out of a criminal life along with a stick in the threat of punishment. Both the carrot and stick, experts said, are crucial to the idea.

As a 2019 review of the evidence from the Campbell Collaboration found, the studies focused on deterrence are largely positive. The problem, the review cautioned, is these studies tend to be of lower quality — there still are no randomized controlled trials, as far as I can tell, on the strategy as a whole.

Given that lower-quality research in criminal justice tends to find more favorable results for the studied intervention, the results are promising but should be taken with some caution. “My personal view is we just don’t know if [focused deterrence] works,” Jennifer Doleac, director of the Justice Tech Lab, told me, acknowledging that other experts disagree.

The research on police isn’t perfect

A big issue with all of these strategies is that they can fall apart as a result of shifting leadership and priorities. Trying something different from a more traditional model of policing requires a strong commitment from those at the top. Princeton sociologist Pat Sharkey, who’s studied policing, went so far as to tell me that “passionate, competent, well-funded leadership is way more important than the specifics of any particular model.”

Another major problem with many of these studies, noted in a report on proactive policing by the National Academies of Sciences, Engineering, and Medicine, is that they often don’t measure the costs of policing — not just the financial costs, but the burden police can often place on a community.

For example, the NBER study that concluded each cop leads to a reduction in homicides also found more officers lead to “more arrests for low-level ‘quality-of-life’ offenses, with effects that imply a disproportionate burden for Black Americans.” That highlights one of the main criticisms of police raised by movements like Black Lives Matter: that officers harass people, particularly those of color, over minor problems, and those incidents can escalate to police killings — as was true in the deaths of Eric Garner and George Floyd.

This matters for the effectiveness of police at combating crime. If a policing strategy reduces crime and violence but also causes a community backlash due to a sentiment of widespread mistreatment, that approach is likely unsustainable. It could even make crime worse: If a community backlash is strong enough, people will stop cooperating with the police. They may even believe they can no longer trust the law and turn to violence instead of the police to settle their own problems. (This is one potential cause of murder spikes over the last year and over 2015 to 2016.)

So even if, say, New York City’s aggressive stop-and-frisk strategy was successful at reducing crime — though at least some research found it wasn’t — it also inspired a significant backlash, a bevy of legal challenges, and protests. Those costs have to be weighed with the benefits.

That’s why the discussion among experts isn’t just whether police can reduce murders but how to use police most effectively. Many believe there is a way to maximize the benefits of police — the homicide reduction — without as many, if any, of the downsides. But that would likely require tapping into approaches that focus on specific hot spots, problems, or individuals that disproportionately contribute to crime or violence instead of casting a wide net that hassles and burdens entire communities.

To put it another way: Evaluating police work, from stops to more aggressive actions, is nuanced, requiring a comprehensive look at the effects on a community. “Stops can be good or bad,” Aaron Chalfin, a criminologist at the University of Pennsylvania, told me. “People on the left think [all stops] are bad; people on the right think they’re good. And it’s not that at all.”

The evidence on alternatives to police is weak

The potential harms of policing are why people want other approaches to begin with: What if there’s an alternative to policing — one with the upsides of law enforcement but none or at least fewer of the downsides?

Unfortunately, there’s little evidence for such an approach yet.

One of the problems, as noted by researchers like Caterina Roman and a 2020 report by the John Jay College of Criminal Justice Research and Evaluation Center, is that there just isn’t as much research into alternatives to police as there is research on the police. The John Jay report argued websites like, which many levels of government rely on, favor policing approaches “because studies of policing interventions (i.e., hotspots policing and focused deterrence) are strongly supported by public and private funding bodies.”

Roman was more blunt in an interview with the Harry Frank Guggenheim Foundation’s Greg Berman: “I think what’s not understood is that we don’t have good evidence on prevention, because we don’t research prevention.” That’s in part a function of researchers’ interest in policing over alternatives but also due to ease of access — policing strategies are just more prevalent around the world than prevention approaches.

Still, there’s some research into alternatives. One widely publicized approach, violence interrupters, uses locally trusted community liaisons — typically people who previously were part of gangs or took part in criminal activities — to break up conflicts before they escalate into violence. An award-winning documentary threw support behind the idea, and President Joe Biden’s administration has shown support for it.

But the research on interrupters ranges from weak to disappointing. A 2015 review of the evidence published in the Annual Review of Public Health looked at a handful of studies on the model in several American cities. None of the studies had fully positive results. The best result, in Chicago, indicated that the approach perhaps produced positive effects for shootings in four of seven evaluation sites — barely better than a coin flip. One program, in Pittsburgh, was so ineffective that it “appeared to be associated with an increase in rates of monthly aggravated assaults and gun assaults” in some neighborhoods.

The 2020 John Jay report was a bit more positive on interrupters but ultimately concluded the findings were “mixed.” The studies conducted so far are low-quality, with no randomized controlled trials completed to date. “It’s concerning,” Harvey, who helped write the John Jay report, told me. “It really is an example of weak evidence.”

There are some approaches to crime and violence with stronger evidence behind them, including summer jobs programs, raising the minimum age to drop out of school, greening vacant lots, more streetlights, more drug addiction treatment, better gun control, and raising the alcohol tax.

But these other approaches were all evaluated in a world where police exist, so even the positive research can’t demonstrate that these are necessarily true alternatives to police.

Another issue is non-police interventions tend to require a longer-term view rather than promising to reduce crime, especially violent crime, quickly. These interventions help address the root causes of crime and violence, from poverty to drug addiction. But it takes time to lift people and places from poor conditions, hence studies on alternatives producing results over months or years. Policing approaches, meanwhile, tend to produce effects within weeks or months, since it turns out people can be deterred from crime or violence quite quickly once officers are deployed on a block.

This is why interrupters seemed so promising: By breaking up potentially violent conflicts on the spot, they could have more short-term effects. But that simply hasn’t been proven in the research.

That said, a real advantage to the alternatives is they don’t come with major downsides. If a policing approach fails to reduce crime, it can still produce a huge burden on a community through more incarceration and everyday harassment by officers. If an interrupter approach fails, at least no one was directly hurt in the process, though there is a potential opportunity cost if the program crowds out more successful approaches.

“We know Cure Violence [interrupters] are unlikely to do dramatic harm,” Doleac said. “But focused deterrence, if it backfires, could be very bad.”

In fact, the alternatives often come with other benefits. Even if raising the school dropout age doesn’t reduce crime, it can still keep kids in school. Even if drug addiction treatment doesn’t cut crime, it still helps people overcome addiction. And so on.

Ultimately, it’s that lack of harm that makes the alternatives to policing worth trying and investigating. Maybe these experiments will produce a fantastic method for fighting crime in the end. If not, at least no one was hurt and maybe some were helped in another way.

But, at least for now, there’s no good evidence that the alternatives can replace the police, Meanwhile, policing has strong evidence suggesting it really can work to cut crime and violence.

“The idea that we can reduce the violence we’ve been seeing without any use of the police is not evidence-based; it’s an aspiration, and it’s a high-risk idea,” Chalfin said. “A balanced portfolio feels like the lowest-risk strategy to me.”

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