But making body-worn police cameras better accountability tools is only half the challenge, when one realizes that New York City soon will have 20,000 police officers wearing cameras pointed at the public all day, every day. Before long, the NYPD and other police departments around the country will have a huge cache of footage of people in all walks of life, with citizens in black and Latino communities particularly likely to be recorded on video, given the concentration of policing in their neighborhoods. With facial recognition software already used by the NYPD to match images to its mug shot database, it’s only a matter of time before that technology is used in concert with body-worn camera systems. One need not indulge in Orwellian fantasies to recognize that body-camera programs threaten to become powerful tools of mass surveillance by the police.

If a body camera falls off an officer, it’s not doing its job, and potentially vital evidence is not being captured. It is therefore imperative that you select a camera mounting system that works well with your agency’s uniform and work practices. Options vary from the conventional center-chest magnetic mount, to brackets that interface with MOLLE and Peter Jones / Klick-Fast load-carrying systems.

Not all cameras can. You need to specifically find a vendor that has both body cameras and in-car cameras that are built to sync with one another. Among the few vendors that do offer this capability, the level of integration will vary.

Pre-event (also called pre-event buffering or pre-buffering) is a standard industry feature with police body cameras. Unlike commercial cameras, which begin capturing content when you press record, police body cameras need to be able to include contextual information into recorded incidents. The reason for this is that something relevant usually happens right before an officer presses record on his body camera, and that context should be included in evidence. This is facilitated by pre-event. The length of time that is prepended onto an incident to be included with each incident is typically dictated by agency policy and administratively controlled.

Body cameras that support pre-event (and proprietary features such as Record-After-the-Fact) are technically always recording, though the footage is not uploaded into evidence unless a recording is initiated. Expectations of privacy by officers and citizens must therefore be carefully assessed whenever a body camera program is initiated.

The battery life for a body camera will vary from one manufacturer to another. The minimum is often 6-8 hours, with 12 hours typically defining the high end. Bear in mind, shifts can run long, and officers may ask to use their cameras for side jobs, which will place additional burden on your camera's battery requirements. Since many agencies pool their body cameras, if your camera cannot easily replace the battery, you will need to plan time to recharge the cameras between shifts. If battery life is important to your agency, you should consider a camera that has a replaceable battery.

Video’s power to improve policing lies in the fact it makes us all eyewitness to police-civilian interactions, ranging from tragic shootings to more quotidian but nonetheless disturbing stop-and-frisks, which are common and, as a federal judge in New York found in 2013, often unconstitutional. Video provides compelling evidence of police misconduct and can be used to train, discipline, fire and even prosecute officers. It’s also a potent tool for exonerating officers falsely accused of misconduct. Ultimately, the aim is avoiding illegal, inappropriate police-civilian interactions, because everyone involved acts differently knowing a camera is rolling.

The national movement toward body-worn cameras has been driven by tragedies over the past several years in which civilians — frequently black men and boys such as Eric Garner in Staten Island, N.Y., Walter Scott in South Carolina, and 12-year-old Tamir Rice in Cleveland — have died at the hands of police officers. Killings that, at an earlier time, would have likely disappeared in the fog of police obfuscation have exploded into national controversies for the simple reason that they were caught on video.

To balance citizen protection with citizen privacy, the NYPD program needs these safeguards: First, all body-camera footage should be stored with and controlled by an agency independent of the police, with strict rules governing access to the footage. While any government possession of the footage poses privacy risks, we are most concerned about mass-surveillance video archives in the hands of law enforcement.

The NYPD’s program illustrates how these initiatives can run into trouble. Importantly, rather than requiring officers to turn on the camera whenever an officer seeks to question a civilian, as advocates had demanded, the NYPD policy requires recording only when the interaction rises to the person being searched, arrested or “suspected of criminal activity.” As a result, many low-level investigative encounters that can quickly escalate in circumstances where turning the camera on may not be safe or feasible will not be recorded. Moreover, the policy has precious few details about supervisory review, and doesn’t include language about consequences of noncompliance, simply noting in an accompanying report that officers face “possible discipline after the conclusion of a 90-day period of field training” if they fail to adhere to departmental guidelines.

Now is the time to make sure body-worn cameras become tools of reform, not mass surveillance. With modest but critical improvements, the NYPD’s program can become a national model.

Every body camera system needs a “back end” solution for storage, management, processing and secure sharing of video evidence. For very small agencies, this can be as simple as a program running on a laptop. For larger agencies, it will be a high-capacity on-premise server or a cloud-based application. When specifying your solution, you should use your video evidence retention policy to calculate exactly how much storage you will need. Some manufacturers will require you to pay large fees for storage, and even larger fees if you exceed your contractual allowance. Be sure to research the storage costs associated with each vendor.

Live streaming of video from a body camera has so far had low adoption in law enforcement. Every camera is required to have a reliable broadband connection, which can be expensive and administration-intensive. Also, the impact on battery life will be significant, possibly leading to premature shutdown of cameras during extended incidents. In-car video camera systems do not carry the risk of battery depletion, so it is recommended that all vehicle systems are configured for live-streaming.

Compounding this problem is the fact that officers can get quick access to most videos, which gives them the ability to build a one-sided public-relations narrative, while victims of misconduct are left with only their own accounts as evidence. In other words, the NYPD policy further stacks the deck against victims.

But the efficacy of this technology depends on how it’s used, and the NYPD’s recently released body-camera policy illustrates just how important it is to get the details right, starting with the on/off button. Because some of the things that take place during an officer’s shift shouldn’t be recorded (such as conversations with confidential informants, undercover officers or child victims), body-camera programs rely on officers to turn the cameras on and off at the appropriate times. This means body-camera rules must properly specify which incidents are to be recorded, and departments must be vigilant in assuring that officers don’t manipulate cameras to avoid recording misconduct.

Finally, other than situations in which video will be used to resolve a complaint, in a criminal prosecution or in a disciplinary proceeding, videos should be destroyed as quickly as possible (recognizing that videos that are altered so individuals cannot be identified may remain in the public realm). After all, the best way to minimize abuse is to minimize the size of archives.

It is strongly recommended that all sworn officers are equipped to record every interaction with citizens. This should include community liaison officers, technicians, enforcement officers and school resource officers as well as patrol officers. You should consider equipping other personnel with body cameras if they regularly interact with the community as well.

Body cameras are becoming an increasingly important tool for police officers. They help to capture an unbiased perspective of an incident and provide crucial evidence for investigations. When researching the best body camera for your agency, you want to be sure that the solution you choose meets the technological, practical and policy requirements of your agency.

As your body cameras build up large volumes of video evidence, it will become increasingly important that you manage the material efficiently. To accomplish this, you will need to add tagging and metadata. Some video systems can also be configured to act based on video metadata: for example prioritizing the upload of violent crime video before that of traffic citations.

A body camera’s “field of view” determines how much of the scene in front of the camera will be recorded. Too narrow a field of view will result in missed evidence. Too wide a field of view will cause “fish-eye” distortion. Some body cameras employ distortion correction technology to help capture a broad field of view without the strong distortion that would otherwise come with the wide angle lens.

Another accountability flaw with the NYPD program is that it virtually eliminates the public as eyewitness. To get access to NYPD videos, the public and press must file open-records requests, to which the department can take months just to respond, with actual production often taking far longer. By contrast, the Seattle Police Department, after blurring body-cam footage to protect the identities of individuals depicted, posts its videos on YouTube. For police body-camera programs to succeed as accountability reforms, the videos cannot be secrets hidden inside police departments.

Missed recordings are a significant issue for agencies with body camera programs. Most agencies have a policy which mandates camera activation when interacting with members of the community, but, in some circumstances, officers simply do not have the time to press record. Because of this, you should consider features like Record-After-the-Fact, that allow authorized agency officials to retrieve video footage from a camera’s memory, even when the record button was never pressed.

Next, recording must be strictly limited, with express prohibitions on filming lawful civilian behavior, including political and religious activity, if that behavior doesn’t implicate a law enforcement necessity. To assure these restrictions are honored, body-camera recordings should be reviewed by authorities outside the police department, with systems in place to immediately halt improper videotaping.