What if the so-called "Ferguson Effect" — the controversial and unproven notion that increased scrutiny of police sparked a law enforcement slowdown — turned out to be a good thing?
Researchers in Baltimore believe they've found evidence of just that.
They came across it in an unexpected place — not the crime rate, but arrest data.
The numbers showed that cops went easy on relatively minor, non-violent offenses like traffic violations, a use of discretion that many reformers say is key to improving the relationship between police and communities where people feel they are unfairly targeted.
The discovery was part of a Johns Hopkins University study that sought to unravel the impact of the August 2014 police shooting of Michael Brown in Ferguson, Missouri. Law enforcement officials around the country, including FBI Director James Comey, have blamed a spike in homicides and shootings in some cities on the heightened criticism of police following Brown's death. The backlash, including a rise in the use of cell phones to capture police activity, made officers less inclined to challenge people on the street, the officials say.
But a growing number of researchers have said there is little proof of a Ferguson effect. They've pointed at crime data showing few links among places where violence and lawlessness are on the rise. They warn that it could take years to understand the recent crime spikes.
Baltimore is arguably America's most extreme case, a place of chronic violence and poverty with a deep history of distrust between citizens and the police. Last April, a 25-year-old man named Freddie Gray died in police custody, sparking a riot and days of unrest. Homicides spiked, making 2015 one of the deadliest on record. Anthony Batts, who was fired as police commissioner following the unrest, later said that his officers "took a knee" when they felt they weren't getting enough support.
Johns Hopkins sociologist Stephen Morgan decided to try to measure how the unrest in Ferguson and the death of Gray played a role in what happened in Baltimore. He and a researcher broke down crime and arrest data into periods — the Ferguson period, covering eight months between Brown's death and Gray's death; the Gray period, spanning the three months following Gray's death; and the Davis period, starting with the appointment of new Police Commissioner Kevin Davis in July 2015 and lasting through the end of the year.
They found that during the Ferguson period, crime remained historically stable, but arrests fell by 19 percent. They broke the numbers down further, and saw that the downturn was almost completely driven by a drop in arrests for less serious crimes, such as property destruction, traffic violations, prostitution and disorderly conduct — scenarios where officers have a wider range of discretion to decide whether to take someone into custody.
Morgan interpreted that as a strong sign that police took a "lighter touch" on minor offenses, perhaps out of concern that their conduct would become the subject of controversy. That shift had little impact on the crime rate.
"I do think we provide some pretty compelling evidence that it is possible for the police to use discretion, to use alternatives to arrest, in a place like Baltimore without influencing the pattern of crime," Morgan said.
That is why Morgan says the eight months before Gray's death could represent a "sweet spot."
"In an environment like Baltimore, where there is a pretty strongly held view among members of some communities that police have been too tough and too brutal, it is possible that you can have more community-responsive policing, a lighter touch, and not increase the crime rate," he said.
But whether that was purposeful, Morgan can't say.
"Do we have direct evidence that officers were reflecting on the scrutiny of them and were using discretion? No, we can't get in the heads of police officers, or hear their conversations with superiors about discretion. We don't have access to that. But it does seem reasonable to think that police officers aren't unaware of what's going on in the press."
Because the arrest data only went back to 2013, Morgan said he couldn't tell if the decline was part of a longer trend, perhaps driven by a backlash against stop-and-frisks. But the drop in arrests after Brown's death was remarkable.
The next part of Morgan's analysis, the Gray period, was much less surprising.
"Everything fell apart," Morgan said.
Crimes of all types, violent and non-violent, spiked, for an overall increase of more than 11 percent. The drop in arrests became much more pronounced, from 19 percent to 30 percent, "consistent with the widely discussed conjecture that the Baltimore police pulled back from some routine policing in response to a perceived lack of support from the city's leadership," the researchers wrote.
It is difficult to tell if Ferguson had anything to do with the crime spike, they said. But the steep drop in arrests might reflect "an accentuation" of the Ferguson effect, exacerbated by "a decline in cooperation from the community that made police work more challenging."
In the final phase, after Batts was fired in July 2015 and Davis took over with a new emphasis on community relations, crime began to abate, while arrests climbed to levels similar to those during the Ferguson period, the researchers found.
A Baltimore police spokesman did not respond to a request to comment on Morgan's conclusions. But the spokesman, T.J. Smith, said in an email that the city was on track to put a lid on the crime spike, with help from a more supportive public.
"We believe the community is ready and willing to rally around the Police Department's efforts to drive down crime," Smith said.
Morgan acknowledged that his study is just a piece in a broader effort to understand the impact of Ferguson on American policing. Much of that work needs to be done on a local level, he said, in order to understand the variety of factors that impact crime.
"We hope that other people will do what we've done elsewhere and help us get to the bottom of this," he said.