Several years ago, when terrorism, immigration, and unrest in suburban Paris were at the top of the news in France, a French police officer confided to a researcher: “If you consider different levels of trafficking, it is obviously done by blacks and Arabs.

“If you are on the road and see a black man or a man with Arabic features, you say to yourself, ‘He doesn’t look French,’ and then you might stop him to see if he has papers.”