Story highlights Brandon del Pozo says he's confronted -- and controlled -- his own occasional momentary rage as a cop

He says criminals act on such emotions; cops can't. This is why Trump's remarks to cops on violence were so offensive

Brandon del Pozo is the chief of police of Burlington, Vermont. He served on the New York Police Department from 1997 to 2015, where he commanded two patrol precincts. He is an executive fellow at the Police Foundation in Washington. The opinions expressed in this commentary are solely those of the author.

(CNN) When I was a New York Police Department cop in East Flatbush in 2000, I once rushed into an apartment building with fellow officers on a call of an assault. We found a boy in the hallway under attack. He was crying, and bleeding from stab wounds inflicted by his mother's boyfriend. The boy ran into my arms. Our sergeant confronted his attacker. He could have shot the man. Instead, he fought him into submission.

Brandon del Pozo

The boy had been stabbed because he had called the police while the man was attacking his mother. She was lying on the hallway stairs in a pool of blood. That her son had served as a distraction was probably the only reason she survived. "You saved our lives," the boy sobbed. He hugged me. His blood and tears wet my shirt.

As the suspect sat there in handcuffs waiting to be led away, I asked him why he had stabbed a child. "Boy gotta learn not to get in a man's business," he said. "So now he learned." A fury rose within me that nearly caused me to shake. "We should have shot you," I said.

But we didn't shoot him, nor did we lay a hand on him once he'd surrendered. Policing requires dealing with the emotions cops are bound to feel when they witness the worst things one person can do to another. It is criminals who act on these emotions and attack other people. Restraint is what separates policing from vigilantism.

Now we have a President who appears to want police to satisfy their primal urges. Either as a joke -- as White House press secretary, Sarah Huckabee Sanders has now suggested -- or as one of many true things that have been said in jest, President Donald Trump addressed a roomful of officers on Long Island on Friday and invited them to be "rough" with their suspects. He advised them to be free with their hands as they shoved arrestees into squad cars, to "not be too nice." His grin and his pause for an ovation erased any uncertainty about his message.

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