Peter Moskos is a former Baltimore police officer and an assistant professor at the John Jay College of Criminal Justice. A version of this essay also appeared on his blog, Cop in the Hood, and in the West Side Spirit.

Karen Schmeer, a friend of a dear friend, was killed on January 29 while carrying groceries home on Manhattan’s Upper West Side. She was killed by a speeding car filled with drug-shoplifting hoodlums fleeing the police. The impact knocked her out of her boots and flung her through the air, half a city block.

Let me be clear: the police did not kill Karen Schmeer. Criminals did. Let them rot. But their guilt does not absolve the police of responsibility.

Karen’s death is more than a simple tragedy. Karen wasn’t just in the wrong place at the wrong time. Karen might be alive if police did not bend or break the exact rules put in place to prevent this kind of senseless death.

Let me be clear: the police did not kill Karen Schmeer. Criminals did. Let them rot. But their guilt does not absolve the police of responsibility.

While it is the job of police to catch crooks, it’s not always their job to chase crooks. Not in cars. Cars are dangerous.

Police say they weren’t in pursuit at the time of the crash, but witnesses, according to the Daily News, “saw the car weaving in and out of traffic going north on Broadway with a squad car with lights and sirens blaring in hot pursuit.” Why the discrepancy? Because police should never be chasing suspects up Broadway at 8 p.m.

You don’t need to pull the trigger to be guilty of murder. You don’t have to want to kill somebody. You do need to accept the likely consequences of your actions. This is what moral responsibility is about.

New York, like most cities, forbids car chases “whenever the risks to [police] and the public outweigh the danger to the community if the suspect is not immediately apprehended.” That’s pretty much all the time unless it’s Osama Bin Laden himself at the wheel.

Car chases aren’t worth it. They often end in some crash. And the pursued car does not have the emergency lights and sirens to warn people out of the way. The car that killed Karen didn’t even have its headlights on.

The NYPD pursuit policy is based on the only effective way to reduce the danger of a car chase: don’t do it. For police, it’s as simple as it is unsatisfying.

Police love a good chase, and there are informal rules to keep your supervisor from stopping the fun. Don’t “chase.” Instead, “follow.” Don’t get on the radio unless your voice is calm and your siren is off. When the suspects bail and run, the one you catch is the driver. If, God forbid, something really bad happens, say you lost contact before it happened.

We all know that driving is dangerous — especially so for police — and we all know people who have been hurt and killed in car crashes. When I was a rookie cop on the streets of Baltimore and driving too fast to some call, I was confronted by my partner: “Do you know anybody [out there]!? Would you cry if anybody died?!” My sergeant put it another way, “I think of my wife or children in a car. They may die. For what?” This was the wisdom of experience. The message was simple: slow down.

Still I couldn’t resist the thrill of the chase. I remember one fondly, on small empty city streets in the middle of the night. A guy with a van was speeding, ran a red light, and wouldn’t pull over. It ended OK. The guy bailed and didn’t crash. I caught him. Nobody got hurt. I had a blast.

Three months later, when the judge saw my suspect in court, he said, “I know you! You’re a drug dealer.”

Taken off guard, the young man replied meekly, “I used to be a drug dealer.” Then he requested a jury trial. When I talked to him later, he said, “That judge doesn’t like me. I used to deal, but I don’t play that no more.”

“Then why did you run?” I asked.

“I didn’t have a license… And I was little drunk.” He was also backing up five years of prison time. He got off with a $500 fine for a suspended license.

I didn’t need to chase that guy, but I did it for the thrill. When I look back, I count my lucky stars nobody was killed. I made a dangerous situation worse by going the wrong way down one-way streets and pushing another driver past his limits.

Had Karen Schmeer walked in front of the car I was pursuing that night and been killed, I would have tried to cover my ass with the exact words a NYPD spokesman used in this case: “Cops tried to pull over the suspects minutes before the crash, but they lost the car momentarily. When they caught up with the vehicle, it had already struck Schmeer, as well as several other vehicles.” Maybe that’s true.

But I’m at least willing to say I was wrong.