Who will watch the watchers? What if all watchers were required to wear a video camera that would record their every interaction with citizens? In her ruling in a recent civil suit challenging the New York City police department's notorious stop-and-frisk rousting of residents, Judge Shira A. Scheindlin of the Federal District Court in Manhattan imposed an experiment in which the police in the city's precincts with the highest reported rates of stop-and-frisk activity would be required to wear video cameras for one year.

This is a really good idea. Earlier this year, a 12-month study by Cambridge University researchers revealed that when the city of Rialto, California, required its cops to wear cameras, the number of complaints filed against officers fell by 88 percent and the use of force by officers dropped by almost 60 percent. Watched cops are polite cops.

Jay Stanley, a policy analyst with the American Civil Liberties Union (ACLU), calls police-worn video cameras "a win/win for both the public and the police." Win/win because video recordings help shield officers from false accusations of abuse as well as protecting the public against police misconduct. The small cameras like the AXON Flex from Taser International attach to an officer's sunglasses, hat, or uniform.

In order to make sure that both the public and police realize the greatest benefits from body-worn video cameras, a number of policies need to be implemented. For example, police officers must be subject to stiff disciplinary sanctions if they fail to turn their cameras on each time they interact with the public. In addition, items obtained during an unrecorded encounter would be deemed a violation of the subject's Fourth Amendment rights against unreasonable search and seizure and excluded as evidence, unless there were extenuating circumstances, such as a broken camera. Similarly, failure to record an incident for which a patrolman is accused of misconduct should create a presumption against that officer.

Officer-worn video cameras do have the potential to violate the privacy of citizens. After all, the police frequently are dealing with people when they are having one of the worst days of their lives. For instance, police often enter people's houses to investigate incidents. In such cases, video of someone's literal or metaphorical dirty laundry is nobody else's business. Consequently, Stanley argues that strong rules regarding the retention, use, and disclosure of videos from police-worn cameras must be established and enforced. For example, videos should be retained for no more than 30 to 60 days, unless flagged. Of course, if the video contains evidence of a crime it should be retained just as any other evidence would be. Flagging would also occur for any incident involving force or a citizen complaint. With the appropriate strong privacy protections in place, very little of police-recorded video would ever be retained or viewed.

Officers should also be required to notify people that they are being recorded. Some preliminary evidence suggests that both police and citizens behave better when they know that they are being recorded. Additionally, the police should not have discretion to release any video to the public. For example, police would be barred from "leaking" videos like that of the drunken actress Reese Witherspoon being arrested in Atlanta for disorderly conduct after a traffic stop. (For what it is worth, the Atlanta police department denies releasing the Witherspoon scene.) Anyone who is recorded, on the other hand, should have access to the video and they should be allowed to consent to public release. Subjects who are incidentally recorded should be blacked out or blurred if the video is released. (The ACLU's Stanley notes that video used as evidence in a public trial would likely be made available to the public.)

Besides those privacy concerns, what possible objections could there be to requiring every officer to wear a camera? Some contend that since practically every citizen can now record police activity using their cellphones, police-worn cameras will be unnecessary. But some states have made it illegal to record people in public without their consent, and the police are often adamant about enforcing that prohibition when the camera is turned on them. Even when the law does permit recording without consent, the police have, in some cases, confiscated a citizen's cellphone and allegedly erased inculpating video.

In addition, citizen recordings will often be incomplete or misleading. People typically start recording only after an encounter turns aggressive, so the context of what is happening is lost.

Won't police officers resist wearing video cameras? Initially perhaps, but most patrol officers are now becoming comfortable with dashboard cameras in their cruisers. A 2004 study for the International Association of the Chiefs of Police found that in cases where police misconduct was alleged, in-car video evidence exonerated officers 93 percent of the time. The same report further noted that dashboard cameras enhanced officer safety, improved agency accountability, reduced agency liability, simplified incident review, enhanced new recruit training, improved community perceptions, helped advance case resolution, and enhanced officer performance and professionalism. In fact, the Atlanta police officer in the Witherspoon dashcam video does come off as quite professional. Body-worn cameras will clearly augment all of those objectives.

The upshot of obliging police to wear video cameras is that it turns the tables on functionaries of the surveillance state. It gives citizens better protection against police misconduct and against violations of their constitutional rights. And it protects good cops against unfair accusations, too. Requiring police to wear video cameras should be universally adopted sooner rather than later.