Measuring racial profiling: Why it’s hard to tell where police are treating minorities unfairly

Donald Trump has waved the words “stop and frisk” around like a banner call to cure violent crime in American cities.

That means it’s time to take a look back at one of the primary criticisms of this police practice: racial profiling.

The American Civil Liberties Union defines racial profiling as “the discriminatory practice by law enforcement officials of targeting individuals for suspicion of crime based on the individual’s race, ethnicity, religion or national origin.” This includes police using race to determine which drivers to stop for routine traffic violations or which pedestrians to search for illegal contraband.

The inevitable question is what percent of minorities the police should stop, statistically. But the default methods for deciding who is guilty of racial profiling are not statistically sound. We are working with the Bureau of Research and Analysis at the St. Louis County Police Department to create a stronger metric.