When researchers studied the effect of cameras on police behavior, the conclusions were striking. Within a year, the number of complaints filed against police officers in Rialto fell by 88 percent and "use of force" fell by 59 percent. “When you put a camera on a police officer, they tend to behave a little better, follow the rules a little better,” Chief William A. Farrar, the Rialto police chief, told the New York Times. “And if a citizen knows the officer is wearing a camera, chances are the citizen will behave a little better.”

The Rialto Study now serves as a centerpiece in the national debate about arming police officers with recording devices, and other California units are leading the charge. But there remain concerns about the practice, which break down across three categories: cost, rights, and the study's veracity.

At $900, the devices employed in Rialto would rack up a prodigious cost for cities like New York, which employs 35,000 police officers. (That's $31 million in police cameras.) On the other hand, as a Washington, D.C., report pointed out, such devices would also save money, not only by reducing lawsuits against the police force but also by helping the force to dismiss cases in court with digital evidence proving that police acted appropriately. Allegations of excessive or unnecessary force; unlawful stops, searches, or frisks; unwarranted arrests, tickets, threats, or traffic stops; and disrespectful demeanors or profanity would all "be easier to resolve with the use of video footage," the city concluded.

An area of greater concern for many civilians might be privacy. Do Americans really want police officers taping events that happen in public places or recording information in people's homes, even when they enter legally? As one report on body cameras wrote:

There are hidden social and ethical costs to the inescapable panopticonic gaze itself. If BWCs become common, it means more electronic surveillance, more digitized tagging of individuals, and arguably more challenges to privacy rights.

Finally, Rialto is a small city, with a population of just 100,000, and there are reasonable concerns about grafting the findings of a one-year study onto the the rest of the country. In the study, complaints about officers declined from 24 to 3. Yes, that's a 88 percent decline. But it's also a numerical decline of 21, which sounds less impressive.

Last night's shock-and-awe campaign against the citizens of Ferguson was a noxious stew of racial resentment, overreaction, under-preparedness, and a militarized police unit. A camera pinned to a shoulder is not going to fix all of these problems. But it does offer a simple technological solution to America's warrior-police problem, which has been exacerbated by all the wrong technology. Something has to police the police.