Call it a hunch, precognition, ESP, or intuition, most cops have experienced it: That feeling that something isn't right. That sensation that something bad is going to happen. For some, the impression proves prophetic.

August 1, 1966, Austin, Texas, police officer Billy Speed tells a fellow officer that he's going to turn in his resignation at the end of his shift that day as he feels that he's in jeopardy of being killed soon.

He doesn't get the chance.

Hours later, Speed is killed by mass murderer Charles Whitman firing his rifle from a perch atop the clock tower at the University of Texas at Austin.

Just before starting his shift on August 27, 1913, motorcycle officer Emery Campbell, tells his wife that he had a premonition of dying. That very day, Campbell becomes the first San Diego police officer to be killed in the line of duty.

Such experiences are hardly unique to law enforcement.

In December 2007, Fidel Sanchez-Flores had a premonition of his death. In the days preceding his clearing snow off of an IRS building, he asked a niece to pray extra hard for him because he was sure something bad was going to happen to him. He also made a point of telling his wife that he loved her and that, if he died, he would die happy. The next day, Sanchez fell three stories to his death when the Plexiglas beneath him shattered.

No less than Mark Twain, Rasputin the Mad Monk, Abraham Lincoln, and-perhaps predictably-Nostradamus are alleged to have also had premonitions of their own deaths.

Sometimes, ominous feelings can be explained away, if only on the heels of hindsight and lengthy introspection.

Juan Fangio, an Argentine race car driver, was exiting a tunnel during a Monaco Grand Prix race when he suddenly braked. His decision to brake was fortuitous as he was able to circumvent an accident that'd occurred just beyond the tunnel. He went on to win the race.

But as he normally would have accelerated upon exiting the tunnel, Fangio was mystified as to what caused him to brake. He had no prior knowledge of the accident; track officials made no effort to alert him of the danger ahead. He thought long and hard about his good fortune, going over all of the things that had registered at some level in his mind in the seconds leading up to his braking.

Upon reflection, he realized that he had noticed a perceptible color change in the audience stands as he exited the tunnel: It had gotten darker. The reason? Whereas spectators would normally look towards the tunnel at the sound of the race cars exiting the tunnel, they instead turned toward the accident, the aggregate pool of black hair offering a sharp contrast to what his eyes should have registered, even at high speeds. This singular shift connoted change. And as change in track conditions usually portended danger, Fangio slowed down.

I suspect that at some point in each of our lives we've all experienced a vague sensation of portended doom. A majority of the time, nothing comes of it. Is it because, having the benefit of some psychic foresight, we were able to change a personal choice, thereby altering the course of events? Or perhaps there was nothing to it in the first place?

There are all manner of plausible explanations for why we sometimes have advance inkling that something is in the air.

As Craig Lerner notes in his excellent article, "Reasonable Suspicions and Mere Hunches," cops and citizens are routinely given mixed messages. I believe every American cop should read it.

Firefighters have no shortage of such incidents as evidenced by one Cleveland incident. A fire lieutenant and his men were saturating a residential house fire with water when he suddenly told his men to vacate the house. Moments later, the floor where they'd been standing collapsed: The fire was in the basement of the house, not in the kitchen as they'd initially believed.

While some of his men wondered if it wasn't ESP, Malcolm Gladwell, the author of "Blink," suspects that it was an instance where the man relied on "thin-slicing": the ability to gauge what is really important from a very narrow period of experience.

I'm not saying I believe in precognition, but I'll not arbitrarily dismiss it either. In any event, I do believe that we are sometimes a little more attuned to our surroundings and can sense when something isn't quite right.

So while courts may not recognize an officer's intuition, you might want to give yourself the benefit of the doubt when you suspect something is up. I'm sure that some of you have experienced premonitions that have come true. Write me and tell me about it at Dean.Scoville@policemag.com.