If you've ever had the distinct displeasure of calling a customer service hot line, you've probably heard a soothing voice tell you that "this call may be monitored for quality assurance purposes." It can be comforting to know that there is, in theory, at least, someone out there monitoring customer-service representatives who make life more difficult rather than less. Customer-service representatives dealing with abusive customers take comfort, too, as this kind of monitoring can shield them from false accusations of bad behavior. By reviewing recordings of calls gone wrong and calls gone right, meanwhile, trainees can learn from the sometimes trying experiences of others.

Thankfully, the stakes of customer service interactions tend to be pretty low. The same can't be said about interactions between armed police officers and civilians, which can be a matter of life and death. The turmoil in Ferguson, Mo., vividly reminds us that while most of these interactions go smoothly, far too many of them spiral out of control. We know little about the exact circumstances surrounding the shooting death of 18-year-old Michael Brown. But had the police officer who shot and killed Brown been obligated to wear a video recording device, there is at least some reason to believe that Brown would still be alive.

Over the past few years, the idea of requiring that police officers make use of so-called "body cams" has gained currency. Note that this is quite different from simply allowing civilians to record on-duty police officers, a right that shouldn't even be in dispute. Instead of waiting for a world in which every civilian records every encounter with the police, at least some students of law enforcement argued that police forces themselves should move in this direction. Last fall, Guardian correspondent Rory Carroll reported on the small Southern California city of Rialto, where the local police department has affixed small body cams to all of its officers. The results were dramatic. Carroll cites a jaw-dropping study, which found that in the year following the introduction of the body cams in February 2012, public complaints fell by 88 percent while officers' use of force fell by 60 percent.

The success of the Rialto experiment makes intuitive sense. When we know that we are being observed, it affects our behavior in many ways. We become more aware of how others might judge our behavior, so we feel a not-so-subtle pressure to act in socially acceptable, rule-following ways. Moreover, the existence of a video recording allows police officers to revisit exactly how they performed in high-pressure situations. Our capacity to remember past events is notoriously faulty. There is a universal human tendency to fixate on some things while neglecting others. Video recordings can help correct for these deficiencies. In instances where something does go wrong — due to malice on the part of the police, a civilian or something else entirely — the video provides a record that can help investigators sort out how things really came unstuck. In politically sensitive cases, in which all sides fear getting railroaded, a black box of this kind would be a godsend.

Granted, Rialto is not a major metropolis, and some will no doubt dismiss the success of its body cam initiative as a fluke, or one not easily repeatable in a big, bustling city. Even Bill de Blasio, the New York City mayor who came to office on the strength of his opposition to heavy-handed stop-and-frisk policing, has hesitated to require that NYPD officers wear body cams, insisting that "it's not something that has been perfected yet." The American Civil Liberties Union, however, has endorsed the idea, giving it much-needed liberal street cred. And now the Brown shooting has led a cavalcade of commentators, mostly but not exclusively on the left, to speak out in favor of the idea. Given time, it's easy to imagine body cams becoming standard-issue for police officers in the near future.

But why stop at video recording the police? While I will happily concede that video recording is particularly important for the police, in light of their ability to use deadly force, there are many public servants who have considerable power over others and who are shielded from scrutiny in the absence of video recording.

Public schoolteachers and administrators are the most obvious example. In March, the Justice Department issued an alarming report on racial disparities in school discipline policies. For example, while black children represent only 18 percent of all children attending preschool, 42 percent of all preschool students suspended once are black, as are 48 percent of children suspended more than once. Video recordings could surface whether teachers are systematically biased against black students, if they are disciplining students in an entirely race-neutral way, or if the truth lies somewhere in between. Investigators could identify patterns that could help inform how teachers are trained to manage their classrooms.

What's more, video recording could allow teachers to evaluate their own progress, and to share their experiences with other teachers who can help them think through how to improve their performances. Teachers unions and their allies, however, are not keen on the idea of video recording. In light of the collapsing cost of collecting this data, it's hard to understand why they'd be opposed to it, particularly if the recordings are used primarily for professional development. If anything, video recording could help teachers beat back shrill accusations of incompetence and top-down, one-size-fits-all schemes for measuring effectiveness. Many teachers have, for good reason, resisted the concept of value-added assessments that rely heavily on standardized tests, preferring instead classroom evaluations that involve occasional visits from outside observers. Video recording every class session would give observers far more data to work with, thus giving them a fairer and more complete picture of how well a given teacher is doing day in and day out — not just a brief snapshot drawn from an hour or two.

Some readers will surely be offended by the idea of video recording cops and teachers. They might even invoke the specter of mass surveillance or the spread of closed-circuit cameras, or some other outrage. I see things differently. Privacy is a wonderful thing, but on-duty police officers and teachers in classrooms are not in fact private citizens living their lives as they choose. They are public servants charged with, well, serving the public. Video recording is nothing more and nothing less than a tool for accountability. Those who use their power responsibly and who make a good-faith effort to do their jobs well have much to gain from video recording. Those who abuse their power and who otherwise cut corners will either have to shape up or answer for their actions. If you come across an argument against video recording that doesn't sound like an attempt to avoid accountability, fill me in.

Reihan Salam, a Slate columnist, also writes for the National Review. He is the co-author, with Ross Douthat, of "Grand New Party: How Republicans Can Win the Working Class and Save the American dream."