By Jake Flanagin

“Ferguson, Mo., has become a virtual war zone,” write Elizabeth R. Beavers and Michael Shank in an Op-Ed for The New York Times. “In the wake of the shooting of an unarmed black teenager, Michael Brown, outsize armored vehicles have lined streets and tear gas has filled the air. Officers dressed in camouflage uniforms from Ferguson’s 53-person police force have pointed M-16s at the very citizens they are sworn to protect and serve.”

“The police response has shocked America,” they write, and while extant tensions between the majority African-American town of Ferguson and its predominantly white police department are the focus of the crisis, “the militarization of the police is a dimension of the story that has national implications.”

How did American police departments get their hands on such high-power, military-grade equipment? National Journal’s Emma Roller cites a New York Times report from June, which brought to light the Defense Department’s recycling of U.S. military equipment by giving them to local police precincts. “This despite the fact that violent crime in the U.S. has steadily plummeted since 1993.”

More than 20 years ago, Congress passed a National Defense Authorization Act, “with a clause allowing ‘the transfer of excess personal property’ from the Defense Department to local law enforcement – otherwise known as Section 1208. The clause was included in response to the surge of violent crime and the War on Drugs in the late 1980s,” and “it’s worth noting that at the time, both chambers Congress were controlled by Democrats.”

Voices on both sides of the aisle have called for wide-scale demilitarization of local P.D.s, including Missouri’s own Democratic senator, Claire McCaskill. “We need to demilitarize this situation,” she told reporters on Thursday. “This kind of response by the police has become the problem instead of the solution. I obviously respect law enforcement’s work to provide public safety, but my constituents are allowed to have peaceful protests, and the police need to respect and protect that right.”

Senator Rand Paul (R-Ken.) echoed that sentiment in a column for Time: “The outrage in Ferguson is understandable – though there is never an excuse for rioting or looting. There is a legitimate role for the police to keep the peace, but there should be a difference between a police response and a military response.” And the response in Ferguson foreshadows some worrying prospects about the future of policing, he writes. “When you couple this militarization of law enforcement with a erosion of civil liberties and due process that allows the police to become judge and jury – national security letters, no-knock searches, broad general warrants, pre-conviction forfeiture – we begin to have a very serious problem on our hands.

But there may have been reasonable cause for outfitting local police departments with military-grade equipment in the early ’90s, writes Annie Lowrey for New York magazine’s Daily Intelligencer blog. The U.S. in the late 1980s was in the midst of a nationwide surge in violent crime. And since the passage of the N.D.A.A. in 1990, “the United States has become a vastly safer place, at least in terms of violent crime,” according to Department of Justice statistics. “That’s also true in the state of Missouri. That state’s population has grown by about 1 million residents since the early 1990s, to 6 million. But the number of violent crimes has decreased to 27,155 from 36,602. The number of robberies has collapsed in half. The number of murders and non-negligent manslaughters has dropped from a high of 590 in 1993 to 389 in 2012.”

While Ms. Lowrey admits there’s no concrete evidence linking military-equipped police departments with the decline in violent crime, she isn’t hopeful that political efforts to demilitarize the police will achieve anything substantial. “There’s now a bipartisan movement to demilitarize the police,” she writes. “But it’s worth remembering that there’s defense money on the line.” In June, Congress failed to pass a partial defunding of a Cold War-era bill that, like the N.D.A.A., approved the transfer of military-grade weapons to local police departments. “On aggregate, the members who voted against the measure received 73 percent more money from defense lobbyists than the representatives who voted for it.”

Political viability aside, and regardless of what the public-safety situation in the late ’80s was, “police militarization was a mistake,” writes Kevin Drum for Mother Jones. “You can argue that perhaps we didn’t know that at the time. No one knew in 1990 that crime was about to begin a dramatic long-term decline, and no one knew in 2001 that domestic terrorism would never become a serious threat. But we know now. There’s no longer even a thin excuse for arming our police forces this way.”