“In a 2017 analysis of data from 20 states, researchers at Stanford University found that “white drivers are searched in 2.0% of stops, compared to 3.5% of stops for black motorists and 3.8% for Hispanic motorists.” After the researchers controlled for stop location, date and time, and driver age and gender, they calculated that “black and Hispanic drivers have approximately twice the odds of being searched relative to white drivers.” They were also twice as likely to be arrested. The study found that “black and Hispanic drivers are searched on the basis of less evidence than white drivers, suggestive of bias in search decisions.”
After surveying drivers in the Kansas City area in 2003 and 2004, Charles Epp and two other researchers at the University of Kansas classified police encounters based on the legal justification (or lack thereof) and the amount of discretion involved. They found that black drivers were no more likely than white drivers to report clear-cut “traffic safety stops” (e.g., for running a red light or stop sign, driving at night with headlights off, or exceeding the speed limit by seven or more miles an hour) but were nearly three times as likely to report seemingly pretextual “investigatory stops” (e.g., for an unilluminated license plate, driving too slowly, or no reason mentioned by the officer).
During investigatory stops, Epp and his colleagues reported, black drivers were five times as likely as white drivers to be searched. They were also more likely to be handcuffed and threatened with arrest, and more likely to describe the officer’s demeanor as rude, hostile, or insulting. Blacks perceived investigatory stops as less legitimate than traffic safety stops, while whites made no such distinction. The more stops black drivers had experienced, the less they trusted the police, an effect that was not apparent among white drivers.”