The first time I heard my father say it, I was trailing along behind him, licking an ice cream on a warm summer night in a Glengarry County town not far from our farm.
"Good evening, officer," he said, as we passed a uniformed patrolman. "Lovely evening tonight."
The cop smiled back and said something kind and reassuring, and the lesson was complete.
The rule in our house was clear: the police protect us and deserve our respect.
The heavens would fall on any of us overheard calling them "pigs," the word the hippies were using where the counterculture was flourishing, in places far from Glengarry.
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Another popular phrase back then was "police brutality," words my father also regarded with suspicion and hostility. (Remember, there were no iPhone videos back then, just he-said, she-said newspaper stories.)
Just recently, I was walking from the White House to the CBC bureau a few blocks away, and as I passed a uniformed Secret Service officer, the old reflex kicked in: "Good afternoon, officer."
This cop, though, stared straight ahead through his sunglasses, wordless, barely acknowledging the greeting.
Clearly, if he was going to speak, it would be to issue some sort of order. Everything in his stance said I am authority. Move along.
Or at least that's how it seemed to me. I don't mind saying it: America's police now frighten me.
Their power and their impunity frighten me. And I'm a white, 58-year-old middle-class man. I can't imagine what I'd be feeling if I were a black or Latino kid in Baltimore.
Baltimore crackled with violence and rage this week. The governor declared a state of emergency and called in the National Guard after rioting erupted following the funeral of Freddie Gray, yet another black man who died in police custody.
The times really haven't changed so much. Gordon Lightfoot once wrote a famous song about another governor who did the same thing 48 years ago in Detroit.
The public conversation isn't much different, either.
Liberals are worrying about what triggered the rioting ("...And they really know the reason, and it wasn't just the temperature and it wasn't just the season ...").
Conservatives are pointing out the shameful looting and the rocks and fire, telling us we should be grateful we have brave police to stand between us and anarchy.
Turning the tables
But the reality the modern surveillance society is providing us is impossible to ignore.
Just as the authorities use technology to collect unprecedented data on the citizenry, the citizenry is constantly crowdsourcing video evidence about the authorities, and it's ugly.
It used to be the cop's word against the perp's. Now it's the cop's word against clear video evidence, and the cop still usually prevails.
In Baltimore, as is most often the case these days, bystanders recorded Freddie Gray's takedown by police on their smartphones. Sometime afterward, his spine was nearly severed. He perished in hospital.
But it's improbable that anyone will answer for the killing — that's what it was, after all — in a court of law.
A recent investigation by the Washington Post and Bowling Green State University stated that of the "thousands of people" shot dead by police in America during the last decade, only 54 officers have been charged.
And most of those who were charged were acquitted.
The series examined cases ignored by the national media: a lot of them unarmed people shot at point-blank range. The officers involved always claimed they feared for their lives; juries almost always took their word, even when the victim was shot from behind, execution-style.
The system doesn't really want to document police crime; governments are for obvious reasons reluctant to keep statistics on such shootings ("not necessarily considered an offence") and police close ranks.
In about a fifth of the cases where charges were laid, prosecutors accused police of planting or destroying evidence.
Crimes of passion?
One needs only consult the iPhone video of the South Carolina cop shooting the fleeing man in the back a few weeks ago, then appearing to plant a Taser on his corpse, to see how it happens.
That officer was charged with murder, but only after the video emerged. A conviction will be another matter entirely.
"To charge an officer in a fatal shooting, it takes something so egregious, so over the top that it cannot be explained in any rational way," said Philip M. Stinson, a criminologist at Bowling Green who participated in the Washington Post investigation.
And even then, juries tend to give the police officer the benefit of the doubt.
Stinson, a former officer himself, suggested that many of these police shootings are really "crimes of passion."
"They are used to giving commands and people obeying. They don't like it when people don't listen to them, and things can quickly become violent when people don't follow their orders."
Today, though, even the conservative voices that have for so long defended law enforcement are wavering.
Take some time and browse the libertarian Cato Institute's online National Police Misconduct Reporting Project.
It's a scholarly work, and evidence gathered is weighed carefully; in fact, the last full year for which they have issued a definitive report is 2010.
That report identified 4,861 formal incidents of police misconduct involving 6,613 law enforcement officers and 247 civilian fatalities for that year alone.
If just a fraction of those fatalities were criminal, then the inescapable conclusion is that more people have been murdered by police in America in the last 10 years than by terrorists.
Of course, we are told, we don't know how many terrorists have been thwarted by vigilant behind-the-scenes enforcement.
Well, true. But given the minuscule number of prosecutions, let alone convictions, neither do we know how many of the people who are supposed to be guarding us have gotten away with murder.