Why is the clearance rate in U.S. cities so low?
Watch any TV police drama and chances are, the episode follows the same script. After several riveting twists and turns, the clever detectives, using the latest computers, equipment, and intelligence, track down the bad guy. Crimes are committed, crimes are solved, arrests are made.
In police parlance, this is called the “clearance rate,” or the rate at which a given type of crime ends in an arrest within a year. And we’re bad at it.
Indeed, U.S. law enforcement is the worst in the Western world at solving crimes. Only one-eighth of burglaries lead to an arrest. For rapes it’s only one-third, and for murder two-thirds. Murder clearance rates have generally held steady for thirty years—even as the murder rate has nosedived, albeit for reasons we don’t really know.
There has been, in other words, zero overall improvement in clearance rates. Remember, this is just looking at arrests; conviction rates are certainly lower.
This is not just a problem facing police in low-income urban communities. Rich and gentrifying San Francisco clears only half of its murders, Palm Beach and Long Island only one-third.
Certainly we expect our laws to be honored and justice to be served. But more fundamentally, people are safer when crimes are solved. Homicide rates are highly correlated with clearance rates. If you live in a municipality with below-average clearance rates, you are twice as likely to be murdered. Plus, we know from social science research that the risk of being caught or arrested is what deters criminal behavior, not longer prison sentences. These folks have short time horizons. Catch the perpetrator, you will deter future crime. It should come as no surprise that, as Chicago has struggled with a wave of gang-related murders, the city’s murder clearance rate plummeted to a horrifying 20 percent.
On the other hand, some municipalities—such as Raleigh, North Carolina, or Arlington, Texas—have had consistently high clearance rate, upwards of 80 percent, for decades. And dramatic improvement is possible: Santa Ana, California, went from 30 percent in the early 1990s to near 100 percent today. Washington, D.C., has seen impressive improvement as well. Looking at these model agencies, we can tease out some lessons about what police agencies can do to get there.
Critically, investigations must be intensive, move fast, and be organized. In a crime’s aftermath, the first 48 to 72 hours are critical: Are you responding promptly before witnesses and suspects scatter? Are there enough detectives available to work the long and odd hours until leads are exhausted? Cases are more likely to get cleared if more detectives are working. Detectives also need first dibs in line for any forensic work, data analysis, or evidence acquisition, and the support to remove bottlenecks. For example, Santa Ana’s police department decided to have its own forensics guy in-house rather than waiting weeks to hear back from Sacramento. The DNA testing pause can sometimes kill an investigation, especially if it comes back negative and the real culprit is by that point long gone.
Another important takeaway for law enforcement: The importance of leadership. Are supervisors watching detectives, helping when need be, and making sure detectives are getting resources they need? Cities where supervisors are more hands-off tend to have lower clearance rates. Similarly, how organized is your document system? Are detectives and supervisors able to locate documents quickly and notice trends and connect the dots? Finally, do you have a good recruitment system with high standards for these essential positions? Higher-performing departments tend to have higher standards for hiring detectives, ranging from required tests to mandatory courses in investigative methods.
All of this effort is wasted without cooperative witnesses and the local community. This is especially so with gang-related murders, which are notoriously hard to solve because of witness intimidation. Durham, North Carolina, does serious neighborhood canvassing after a violent crime; you’ll often see the local City Council member out knocking on doors, to help encourage witnesses to come forward and build trust in that community.
This doesn’t require enormous sums of new money. As cities around the country have been financially pressed, some police departments have been hit hard with budget cuts. The share of law enforcement officers per capita in this country has been trending down the last decade. Police departments have been directing a lot of manpower and resources to crime prevention work. They’ve brought aboard data scientists to crunch out algorithms or power more “hot-spot” policing, directing officers to sit on corners most likely to be the scene of the next crime. This prevention is important, but there should be more priority given to raising the clearance rate as well.
Police funding is primarily local, as are felony crimes. Consequently, it’s usually up to local municipalities to solve their own cases without state or federal assistance. There isn’t even a good official national tally on cold cases. That hard work is left to committed investigative journalists like Thomas Hargrove at the Murder Accountability Project. Unlike most other rich countries, there is no national-level review of violent crimes. Texas has an above-average clearance rate, and it might be because Texas Rangers frequently offer extra help to local municipalities that have hit a dead-end in a murder case. Wisconsin also has an above-average clearance rate and an official review system for cases that go cold.
We should all be worried about cold cases, right? Let’s make it a local and national priority and decide that leaving 30 percent of murders unsolved is unacceptable. We know how to improve clearance rates—several cities have figured it out. Let’s get our communities focused on making this happen.