When Michael Brown was shot and killed a little after noon on August 9 in Ferguson, Missouri by police officer Darren Wilson, several eyewitnesses saw what happened. Autopsy results have been released that reveal Brown was shot six times. Word that Brown was unarmed at the time spread fast and for several days, Ferguson was the scene of angry protests by day and unrest by night, to which police responded with tear gas and curfews. On August 18, Missouri Governor Jay Nixon called in the state's national guard troops, which were withdrawn after three days of increasing calm. 
But tensions are still high, and depending on who you ask, you will hear either that Officer Wilson was defending himself against a potentially deadly physical assault by Brown, or that Brown was guilty of nothing more than being black and walking down the street when an out-of-control white cop killed him.
Would a body-mounted video camera on Wilson's chest have made this situation any better? More generally, should cops carry body-mounted video cameras and use them any time they're dealing with the public?
Ironically, the Ferguson police department had reportedly bought some body-worn cameras, but had not yet deployed them at the time of the shooting. For police, using a body-mounted camera is not just a simple matter of strapping one more piece of gear onto your shirt. Some states have laws about recording video without a private person's permission. And video cameras generate beaucoup quantities of data that have to be dealt with somehow, although various services offer cloud-based solutions to this particular problem. Finally, the cameras do cost something, but current prices average in the US$350 range, about what a service revolver costs. And unlike revolvers, the price-performance ratio of video cameras continues to fall, which is why they're showing up in more and more places.
The price of video recording has been falling ever since May 22, 1958, when the first color video recording of a live event was made. On that day, President Eisenhower was scheduled to make a brief address at the new NBC color television studios in Washington, DC. RCA president David Sarnoff, ever alert to the potential for making technical history, arranged for the event to be recorded by the network's new color video recording system. The signals were transmitted over the NBC network to Burbank, California, where an experimental magnetic-tape video recorder captured the half-hour ceremony. Fifty-six years later, what it took a roomful of equipment and dozens of engineers to do then can now be done by one little box strapped to an officer's chest. But does the fact that we can do such a thing mean that we must do it?
Several news reports have cited the experience of the police force in Rialto, California, where all police officers have been wearing pager-size body cameras for more than a year. According to a report in the Wall Street Journal, in the year since the cameras were deployed, the use of force by officers went down 60 percent and complaints by citizens about police misbehavior declined 88 percent.
One possible cause for these remarkable improvements is what might be termed the video-placebo effect. Back in the days when video equipment was relatively expensive, retail stores often bought cheap imitation cameras that looked like real ones but were just dummies—empty boxes. But the sight of them deterred crime about as well as real ones did. Simply publicizing the fact that your officers all wear cameras will change the psychology of both the officers and the people they deal with, even if the video evidence isn't used.
There is, of course, the opposite effect to consider. Sometimes the presence of cameras creates trouble where it wouldn't otherwise exist. Most people are familiar with the fact that protesters are attracted to news cameras like flies to honey. But that sort of thing happens only when publicity is the main goal. For true criminals, publicity is the last thing they want. So it is likely that both citizens and cops will act better if body-mounted cameras are used.
The wide availability of video recordings of police actions can tempt users to give in to a concept summarized by the phrase "the camera cannot lie." While it is true that the camera cannot lie, it can't tell the truth, either. Truth is a property of the immaterial things called propositions, and hardware and photographs aren't propositions. They can provide evidence for the truth of propositions, but the evidence must be evaluated and interpreted by fallible human beings. So if body cameras become as standard a piece of police gear as a badge, lawyers and others concerned with the validity of evidence need to remember the idea that video evidence is like any other kind of evidence, and there's nothing magical or automatically dispute-resolving about it.
Sure, eyewitness accounts of Michael Brown's shooting differed. That is the nature of eyewitness accounts. But we shouldn't fool ourselves into thinking that if only Officer Williams had used a body-mounted camera, that everyone could have just watched the video and gone away in total agreement as to what happened and why. Cameras are helpful in finding out the facts—no doubt about that. I'm glad that engineering progress has made something that used to be affordable only by million-dollar organizations cheap enough to benefit law enforcement personnel all over the world.
But like any other type of evidence, video can be misused. And the procedures for selecting and making such recordings available to both prosecution and defense need to be worked out so that justice is truly served by this new technology. Karl D. Stephan is a professor of electrical engineering at Texas State University in San Marcos, Texas. This article has been republished, with permission, from his blog, Engineering Ethics, which is a MercatorNet partner site.   Notes For nerds interested in the world's oldest color videorecording, it is viewable here and a description of how it was recovered from old tapes and restored is here.