In my own research, I have collected over 50 examples in which innocent people were killed in raids to enforce warrants for crimes that are either nonviolent or consensual (that is, crimes such as drug use or gambling, in which all parties participate voluntarily). These victims were bystanders, or the police later found no evidence of the crime for which the victim was being investigated. They include Katherine Johnston, a 92-year-old woman killed by an Atlanta narcotics team acting on a bad tip from an informant in 2006; Alberto Sepulveda, an 11-year-old accidentally shot by a California SWAT officer during a 2000 drug raid; and Eurie Stamps, killed in a 2011 raid on his home in Framingham, Mass., when an officer says his gun mistakenly discharged. Mr. Stamps wasn’t a suspect in the investigation.

What would it take to dial back such excessive police measures? The obvious place to start would be ending the federal grants that encourage police forces to acquire gear that is more appropriate for the battlefield. Beyond that, it is crucial to change the culture of militarization in American law enforcement.

Consider today’s police recruitment videos (widely available on YouTube), which often feature cops rappelling from helicopters, shooting big guns, kicking down doors and tackling suspects. Such campaigns embody an American policing culture that has become too isolated, confrontational and militaristic, and they tend to attract recruits for the wrong reasons.

If you browse online police discussion boards, or chat with younger cops today, you will often encounter some version of the phrase, “Whatever I need to do to get home safe.” It is a sentiment that suggests that every interaction with a citizen may be the officer’s last. Nor does it help when political leaders lend support to this militaristic self-image, as New York City Mayor Michael Bloomberg did in 2011 by declaring, “I have my own army in the NYPD—the seventh largest army in the world.”