BRUSSELS — Several years ago, as 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."

This police officer was describing a textbook example of "ethnic profiling": law enforcement officials use of stereotypes, rather than specific information about behavior, in deciding to stop, search or detain people.

Ethnic profiling is illegal in Europe. It is ineffective in apprehending criminals. It is counterproductive in the campaign against terrorism. But police officers across Europe continue to use it.