Murders in the United States jumped 11 percent last year, according to federal data released on Monday, but nonviolent crimes declined, an unusual divergence that’s puzzling criminal justice experts.
While an increase in homicide is usually associated with more minor crimes as well, that was not the case in 2015. The number of murders nationally increased by the largest percentage in decades, but violent crimes overall increased just 4 percent and property crimes declined 3 percent.
Despite the increase, American streets remain safe relative to recent years. The rate of murder and manslaughter per 100,000 people (excluding negligent manslaughter) increased to 4.9 last year from 4.4 in 2014, which was the fewest of any year since at least 1961. In 1980, the rate exceeded 10 killings per 100,000.
Still, what to make of the sudden increase in homicides is not clear. Some criminologists say the data is evidence against the “Ferguson effect” — a popular theory that suggests homicides have increased because police have become reluctant to interact with potential criminals on the street. According to this argument, cops fear becoming involved in a violent altercation that could result in protests such as those in Ferguson, Mo., Baltimore and Charlotte, N.C.
Police can deter potential criminals not just by being a watchful presence on patrol. They can stop people who appear to be involved in criminal activity, talking with them to gather information or to disperse people who are fighting. Police can also search civilians for firearms, knives or tools for breaking locks and windows.
These activities make committing all kinds of crimes more difficult, not just homicide. If the increase in homicides were due to hesitance on the part of police to stop civilians, some criminologists say they would expect an increase in other “street crimes,” including burglary and robbery.
However, just 3.1 percent more cars were stolen last year, and the number of robberies increased just 1.4 percent. The number of burglaries declined 7.8 percent, according to the new federal data.
“People who are talking about Ferguson effects — why do you find it in homicide and not burglary?” asked Franklin Zimring, a criminologist at the University of California in an interview earlier this year. “That’s just not very good logic, and it’s not consistent.”
Other experts are not convinced. Alfred Blumstein, a criminologist at Carnegie Mellon University, is one of those who believes that changes in police officers’ behavior might account for the increase in lethal violence last year. He argues that a subtle shift in police behavior might not noticeably affect minor street crimes, since so many of them are committed.
“Undoubtedly, there’s a skittishness on the part of police,” he said. “They don’t want to be caught in some compromising situation and put their own careers, if not their liberty, at risk.”