During most of my adult life, whether working or not, I have seldom been far from a gun. Pistols, shotguns, semiautomatic and fully automatic weapons are at the top of the pyramid of tools that cops use to quell violence or arrest seriously dangerous people. Most of the time, the threat of a gun is all that's needed to make people drop their weapons or otherwise submit. Sometimes that's not enough and an officer makes a decision that he will remake and relive in his mind for the rest of his life: whether or not to pull the trigger.

There are people who believe that some police officers are always on the hunt for an opportunity to kill someone. Maybe there are some like that, but I haven't met any of them. There's more than one reason that, despite extreme danger or tremendous provocation, most cops will go the heroic extra mile to avoid shooting. One is that all departments nowadays go to great lengths, when hiring, to weed out every candidate who would not be a good psychological fit for the job. Most of the hundreds of officers with whom I rubbed shoulders did not project the aura of trained killers waiting for a chance to drop the hammer. They were more often people with well-developed social skills who were above-average in their ability to interact with others. There are not many professions that encounter death more often than law enforcement. Cops know violent death for what it is: not something that happens in a video game or a movie but a sad, ugly event that leaves a wake of grief, often for people on both sides of the action. A person with normal feelings and understanding just doesn't want to go there.

Perhaps above all, every officer knows that a decision to shoot will change his life, and never for the better. Moments after a police-involved shooting, for those in the eye of the storm, the world begins to rotate in a different direction — one they've never experienced before. No matter that he may have, moments ago, thought he was going to die. Never mind that he may have risen to a level of heroism that few ever attain. It makes no difference if he placed himself in the gravest danger to save someone else. Now he's a potential defendant in a homicide investigation, his gun seized as evidence, a blood sample taken, possibly read his rights from a Miranda card. He's off the job, maybe for a while, maybe forever, and it's all beyond his control.

In the days following the shooting, the media will demand to know the identity of the officer and will, sooner or later, be given the information. His family may be forced to go into hiding to avoid camera crews and nut cases. The police department will be restrained in its release of information, not wanting to later find that something that it gave out proved to be untrue. No restraint will be exercised on the other side of the conversation, as interviews with anyone who will talk about the situation are played over and over on cable TV. If the officer is white and the person he shot is minority, that part of the story will outweigh all others. Every man or woman who pins on a badge and carries a gun knows that all of this will happen if deadly force is used. They also know that it's a decision that will probably come on them unannounced and may have to be made in a few seconds.

Nearly everyone can remember some time in life in which he or she felt threatened and intimidated by another person. For people in some neighborhoods, the feeling is there almost constantly. There's an ample supply of sociopaths in our world, people who don't respond to reasoned words or even the threat of legal penalty. The expectation that most of us have is that when we are threatened with violence the police will respond quickly to a 911 call and nullify the threat. We understand that a truly out-of-control person may have to be stopped with physical force. The question is how much or what kind of force?

For a number of years, police officers have been taught the concept of the "force continuum." Imagine a graph-type line running from the lowest form of force (voice commands) up to the highest (deadly force, which usually means shooting). In between the two extremes would be the use of such things as physical restraint; blows delivered by fist, foot, knee or elbow, or the implementation of such tools as chemical irritants, stun guns or batons. The idea is that the officer should move to the point on the continuum at which there is just enough force to overcome the perpetrator's resistance. Nice theory, but not so easy to pull off.

I wish that everyone who wants to weigh in on what constitutes police brutality could at least once experience a really violent struggle with another person. They would find that 30 seconds into the fight, they're already sucking wind. They might be disoriented from a blow to the head or a punch to the solar plexus and be desperate to hang on and recover. They may be unable to create enough space to get at a weapon, even if they now realize they may lose the fight without using it. They'd quickly learn that, in the midst of a struggle, one can't know exactly how much force it will take to win. To not win could lead to the other combatant seizing control of their weapons without the slightest inclination toward moderation.

In recent years it's become trendy to grab your smartphone and hit "record" whenever you see an encounter between police officers and the public. Add to that dash-mounted squad car cameras and "body cams," and there's a vast amount of raw footage of cops doing their jobs — often pretty well, occasionally poorly. Most of the officers I know aren't bothered by the filming except for this: Often it catches only part of the action and misses the rest of the story.

The other problem with videotaped action is that it is used much like instant replay in professional sports. Every Sunday afternoon, we watch terrific athletes do nearly superhuman things on the football field. A receiver leaps high at the back of the end zone, making a fingertip catch as he is hit by a defender. An official crouches nearby, trying to see if the catch was made, whether control of the ball was maintained and if the receiver came down in bounds. It happens with lightning speed, and the official makes the call based on what he thinks he saw. Then the analysts take over, and we all get to see how the official did. We view the play from different angles and, most important, get to see it in slow motion, even frame by frame if that helps. "Look there, Joe, just as his left foot comes down, his heel touches the chalk … he's out of bounds … I think they'll reverse the call." In just that way, the luxury of slow-motion review and time to analyze can make the highly stressed decision of a moment seem like a bad call.

According to Wikipedia, in 2008 there were about 765,000 full-time sworn state and local police officers in the United States, with another 120,000 federal officers. Imagine the number of interactions that 885,000 cops have with the public every day. Given the variety of people involved and the confrontational aspects of many of these situations, it should be no shock that some of them are handled poorly, even terribly. The real surprise is that, even with people's impulse to get some good video footage of cop misbehavior, the actual number of events that raise public outcry is a micro-percentage of the total.

We have every right to expect only the best from police officers. We want them to be honest and respectful, caring and kind. We need them to be aggressive, yet capable of holding back, brave but not brutal. We'd like them to rush to interpose themselves between us and danger, even at the risk of losing their own lives. During the 37-year span in which I was on the job, I saw all of these things manifested over and over by many of those I worked with. I must admit that once in a while I saw something that didn't make me proud. I was working with humans, after all.

Terry Smith served as a police officer for 37 years, first as a uniformed officer with Bloomington, Minn., Police Department, then as a special agent with the Minnesota Bureau of Criminal Apprehension. For the last 17 years of his career, he was the special agent in charge of the BCA's regional office in Bemidji. He drew his gun numerous times while confronting violent offenders but pulled the trigger just once, to fire a warning shot.