There's a fundamental dictum in American law enforcement. It goes something like this: Regardless of whether the subjects an officer contacts are armed, the very presence of the officer brings a deadly weapon to the scene in the form of the officer's duty gun. Therefore, one of the officer's most important tasks is to safeguard his or her sidearm.

That dictum is drilled into you throughout your careers. You hear it in the academy and during in-service defensive tactics classes. There is at least one gun at every incident, it's yours, and you have to protect it.

Today there's another dictum that academy instructors and all other American law enforcement officers would also do well to remember. It goes something like this: There is always a camera watching you, and it would be better if you had one, too.

Consider the case recently in the news involving an officer from the El Monte (Calif.) Police Department. At the end of a dangerous high-speed pursuit, this officer was captured on tape delivering a kick to the head of a proned-out suspect. That video was taken from a news helicopter hovering overhead. And it quite clearly shows an officer kicking an apparently surrendering suspect in the forehead. Other aspects of this video are not so clear.

Since it was taken from a helicopter overhead, the video doesn't capture anything said by any of the participants.

Could anything said by the suspect justify a boot to the brain box?

Well, if all he said was something obscene about the officer's mother, then no. The officer might want to kick the guy quiet, but legally he wouldn't have the grounds to do so. In such a case, audio from the incident might actually be used to hang the officer.

But let's say the suspect said something like, "I've got a gun." Could that be grounds for a boot to the head? Maybe.

Let's postulate that the officer in question can articulate that he had good reason to believe the suspect's words were true, that perhaps he saw a glint of metal, or even a glint of deadly intent in the suspect's eye and the twitch of a hand. Given that totality of circumstances, would he have grounds to kick a surrendering suspect? Maybe. His administrators and possibly a jury would have to make that decision.

One problem that this officer and his attorneys face in this scenario is that the only visual evidence in the case may be the helicopter-shot footage of the officer kicking the suspect. There were—as far as we know—no other cameras on the scene.

But this incident happened away from in-car video cameras. Think how beneficial it could have been to that officer if he himself knew that he had a camera on his body and it was running at the time. It might carry the one angle of the incident that shows he had grounds to kick the suspect.

If such an incident happens a few years from now, the officer involved will likely be equipped with a body-worn video system that captures everything he sees. You can read all about these systems on page 38.

While researching our body-worn video article, we spoke to a variety of agencies that have fitted their officers with some of these systems. Not one of them reported any resistance from their officers. Their officers wanted to wear the cameras.

And with good reason. The International Association of Chiefs of Police reports that "93 percent of officers charged with misconduct are exonerated when video evidence is available." To that I'd like to add, only if the video evidence isn't shot by an amateur videographer (Rodney King), on a passenger's cell phone (Oakland BART), or by a hovering news copter (El Monte).

You are always on video. The only question that you have to ask yourself is whose video it will be? Believe me, you will be better off if the images are captured by your own body-worn or in-car video system than by another interested party. And even if another person videos you performing your duties, your official video will likely provide a better angle and a more comprehensive record of what really happened.