With the recent spate of clashes between law enforcement officers and citizens, many civil rights experts have stated that the outcome of the police investigation would’ve been different had the defendant possessed a video recording of the encounter.

On the surface, that would certainly appear to be true. In fact, reporter Kevin Fagan of the San Francisco Chronicle quoted the CEO of one camera manufacturer that makes a vast majority of the body cams police wear, as saying, “It’s a no-brainer to start using these devices.” Is it a no-brainer? Not necessarily.

Careful thought, study, and discussion should go into the deployment of any devices that impact law enforcement and legal proceedings—and people’s lives—so dramatically.

Let’s first examine the numerous reasons why wearing a body camera is a good idea. (I’d like to acknowledge Chris Schoppmeyer, the vice president for Agency Affairs for the Federal Law Enforcement Officers Association, for assembling this pro/con list and Jon Adler, the organization’s president, for giving me permission to use, and modify, it.)

Police-worn body cams will:

• Reduce false complaints of police misconduct.
• Decrease use of force incidents. (In fact, in Fagan’s article, he notes that this is exactly what’s happened.)
• Improve the behavior of suspects and the quality of evidence gathered.
• Enhance public trust and create safer communities with a return on the investment.
• Decrease litigation and increase cost savings for each law enforcement agency.
• Expedite plea agreements, which will reduce legal and court costs associated with drawn-out trials.

But body cams are not a panacea. For one, there is no federal policy governing body cameras, and state mandates are either nonexistent or inconsistent. This is, of course, reparable and, if handled properly by legislators, will be helpful in setting standards regarding 1) the long-term storage of the recordings; 2) the handling of the footage (in use of force incidents, the involved officers should not be permitted to edit—and chain of evidence needs to be clearly documented); 3) the delineation of what incidents should not be filmed because of privacy concerns (example, a sexual assault case); etc.

With all the aforementioned advantages, what could possibly go wrong? After all, it’s giving a judge or investigative review panel a first-hand view of exactly what happened in an altercation/call. But that’s the problem; it’s not really an accurate accounting of what transpired. Here’s why:

• Unlike a dashboard camera, which is mounted to the car and does not move, the body worn camera has the ability to move its field of view. This is both good and bad—but the important thing is to understand how this can limit your ability to see, in retrospect and onscreen, what occurred. Since the camera has no peripheral vision, what the officer sees in his/her periphery, and more importantly, the threat(s) presented by it—are not represented in the recording. In addition, there’s only one angle being shown. It’d be like trying to have a single umpire at a baseball game and expecting him to get all the calls correct. It would never happen. That’s why there are multiple umpires and the one with the best angle, and proximity, makes the call. However, even four umpires, all looking at the same play, don’t always get it right. Major League Baseball started using instant replay in an attempt to correct this, but despite having cameras showing multiple angles, sometimes it’s still difficult to determine if the correct call was made. Most significantly, upon reviewing a replay from all these cameras, the umpire’s call is overturned 47% of the time. With a single camera, what are the odds a police review board or jury would see all that they need to see to render an accurate judgment?

• Media, social, or judicial condemnation of a law enforcement officer based solely on body worn camera footage might not be a case of justice being served. If a picture’s worth a thousand words, a video is worth perhaps ten million words. Point is, people are swayed by what they see. Jurors will look at a video and believe it represents 100% of the case: but as is clear from this post, it’s a more complex equation.

• Current body cams don’t record physiological and psychological phenomena that an officer experiences under duress. These are high stress situations and, being human, he or she reacts based on a heart that’s pumping faster than normal, breath that’s coming shallower than normal, a visual field that is more focused, and narrower, than normal. Let’s examine that last point: As a survival mechanism, our brains may suppress some incoming visual images that seem unimportant in a life-threatening situation to allow us to zero in on the threat. You’re not even aware of what your brain is screening out. The camera, however, completely misses this variable; it’s like it does not exist.

• Our brain may play visual tricks on us that the camera can’t match. If a suspect is driving a vehicle toward an officer, it will seem closer, larger, and faster than it really is because of a phenomenon called “looming.” As a result, camera footage may not convey the same sense of threat that the officer experienced.

• An officer can usually tell when he or she touches a suspect whether that man or woman is going to resist arrest. The cop may quickly apply force as a preemptive measure, but on camera it may look like he or she launched an unprovoked attack because the sensory cue the officer felt cannot be recorded visually.

• Camera speed differs from the speed of life. Most of us have experienced this phenomenon.

• A body cam only records in two dimensions. Specifically, it cannot capture depth of field, which is the third dimension that’s perceived by the human eye because of its binocular vision; thus, accurately judging distances on footage can be difficult. At the very least, this technical limitation ensures that the recorded footage will be different from what the officer saw. “Different” does not automatically mean “significant,” but it can.

• Time-stamping that is automatically imposed on camera footage is a gross number, generally measuring the action minute by minute. In some high-profile, controversial shooting cases, that is not sophisticated enough.

• A body worn camera could cause an officer to second guess the course of action and impact his decision-making the next time he/she encounters a similar situation. If he/she acted properly but the camera tells a slightly different story because of the above factors, either the officer or his/her superior may inject uncertainty into his/her approach, causing him/her to hesitate next time, resulting in injury or death.

• A body cam is worn in one of three places—none of which approximate the angle of the officer’s eyes. The result is that the angle on film is different from that seen by the cop during the contact. And as alluded to previously, the camera lens is limited to the area where an officer’s squared shoulders are facing.

• The camera only records video—not audio. For law enforcement officers, the ability to capture audio is of equal importance. Critical communication, such as warnings by the cop or threats expressed by the suspect(s), are not captured by the recording. (A further benefit to having audio capability is that in a worst-case scenario where an officer is attacked and injured, he/she would be able to give a description of the suspect even if the camera didn’t capture the attack.) Perhaps future versions of the devices will have audio capability, but for now that’s not part of the equation—even though it needs to be.

A recent Washington Post article by Marc Fisher and Peter Hermann quoted former police chief Jim Bueermann, who now serves as president of the nonprofit Police Foundation, as saying that today’s videos “show only a slice of time, midstream, and the field of view of the camera is very limited.” According to Bueermann, the next generation of body cameras promises views from multiple angles along with technology that will allow supervisors to monitor officers in real time, checking for rising blood pressure and a spiking pulse, “so we can provide a calming, defusing effect and say, ‘Chill out, we’re on our way.’”

In sum, are law enforcement officers perfect? Of course not. Do they always follow the rules? Again, no. Are they always well-meaning? I believe a majority are, but there’s no question there are rotten apples in every agency. They’re human, and as in all professional careers, good and bad are part of the territory. Surgeons operate on patients when they’re intoxicatgd. Engineers and architects, driven by money, use inferior materials and people die. Attorneys collude to do unethical things to reap profit. Politicians take bribes. Religious leaders sexually abuse young men. To expect all cops to be model citizens is illogical.

There’s no question that we need to continuously strive to train law enforcement officers properly, to evaluate them, to weed out those who should not be policing our streets, carrying weapons, upholding the law. We expect professionalism, adherence to procedures, respect, and courtesy. And because people behave better when they’re being monitored by those in power, where judgment can be passed, promotions made or broken, or embarrassment experienced, body cams can, in many cases, assist superiors in achieving this. They are, however, only one tool. And that’s how they should be viewed: not as a magic bullet, but as a potentially useful piece of a comprehensive solution.