The precipitous decline in murder clearance rates in recent decades is normally taken as a sign of falling police productivity and eroding public faith in law enforcement, but a new article in the Annual Review of Criminology suggests that the reasons behind the decline are more benign, writer Matthew Yglesias writes at his Substack publication Slow Boring. In the paper, “The Sixty-Year Trajectory of Homicide Clearance Rates: Toward a Better Understanding of the Great Decline,” Duke’s Philip J. Cook and the University of South Carolina’s Ashley Mancik review the evidence of multiple explanations for the national decline in clearances and land on one that often gets overlooked: that police have gotten better at making murder cases stick, and thus the arrest-to-conviction ratio has gone up as standards have grown more selective. "The new paper shows that the image of falling success rates in the second half of the 20th century is basically an illusion," Yglesias writes.
One of the main upshots of the Cook/Mancik paper seems to be that the FBI’s data on clearances is misleading. According to the FBI, there are two ways a case can be cleared — by arrest or by exceptional means. There’s no requirement that the arrestee actually be convicted or even prosecuted. Even though the clearance rate plunged between 1970 and 2000, the convict-to-victim ratio soared. Over the next 10 years it fell slightly, but remained much higher than it had been when clearance rates were much higher. Yglesias notes that the data used in the paper sample from 19 states because of the difficulty of obtaining comprehensive crime stats. But, he concludes, "I think it’s convincing: the falling clearance rate almost certainly reflects a higher standard for arresting someone, not a falling likelihood of being held accountable." This interpretation of the trend casts new light on concerns about racial disparities in unsolved murders, but it shouldn't obscure the reality that "the clearance rate is a lot lower than we'd like it to be" and it could be improved through better policing and more investigative resources, Yglesias writes.