Forty years ago, I got a lesson in biased policing while I was a student in a criminal law class at Ohlone College near San Jose.
The professor, a retired San Francisco officer, was talking about the use of discretion. He used as an example failure to signal before changing lanes. He pointed out that it would foolish to make a stop every time you witness such an offense and asked for examples of when you should and shouldn’t ignore it.
Most students offered similar examples. “If you see someone a half mile ahead of you on a nearly deserted freeway change lanes without signaling, who cares?” “You should pull them over if they cut someone off,” etc. (All dialogue here is paraphrased, but the consensus was “no harm, no foul.”.)
But then one earnest young white cop said he pulls people over when they are chicano, the term in widespread use at the time. The reason, he explained, is that almost every chicano he encountered was up to no good. Their offenses included drugs, theft, assault, and traffic violations. Half the people he gave tickets to were chicano, he said, because they are lousy drivers.
He seemed proud of himself, and I think he expected the professor to praise him for being more savvy than his naïve classmates. That did not happen, but I’m not sure he got the message.
The professor made all of the salient points (again, I’m paraphrasing): “If half the people you pull over are chicano, it stands to reason that half the tickets you issue would be to chicanos, but if you’re pulling over more chicanos than you should, you’re giving out more tickets to chicanos than you should. If you never pulled over a chicano, none of the tickets you issue would be to chicanos,” etc.
Then he added “Besides, it’s the nature of our job that most of the people we encounter are doing something wrong; most the white people you encounter fall into that category, too, am I right?”
The young cop became defensive and a bit indignant. “Nobody in my family has ever committed a crime!” “The people in my church are all good people!” “There are bad apples, but most white people don’t commit crimes!” Mostly, however, he was indignant at the suggestion that he might be racist.
The discussion went on without resolution until class ended.
I think it still is going on today, 40 years later.