DURHAM -- RTI International, one of the world's leading research institutes, released traffic stop data findings on Thursday revealing black male drivers were disproportionately pulled over in traffic stops during daylight hours.
RTI International researchers analyzed six years of data provided by the Durham Police Department from more than 151,000 traffic stops, from January 2010 through October 2015.
"To test for racial bias in traffic stops conducted by the Durham Police Dept., we employed the veil of darkness method, which is based on the assumption that officers have a significantly diminished ability to observe the race and gender of the driver during periods of darkness,” said Dr. Kevin Strom with RTI International.
Researchers found among stops involving male drivers, the odds that a driver was black were 20 percent higher when the stop occurred during daylight hours than in darkness. Though the results suggest this was the case between 2010-2013, the differences declined. By 2014, the odds of traffic stops involving a driver being a black male in the daylight compared to darkness were indistinguishable.
"Importantly, the relationship between lighting and driver race was conditional upon year, with findings showing racial disproportionality decreasing over time," said Dr. Strom.
Interim Police Chief Larry Smith says the decrease could be from changes in policies, procedures and training.
"We don't know what causes it, the report doesn't show. That's why it's important among us as law enforcement leaders, when we find things like this, to try to address it," he said.
The traffic stop study also showed there was no evidence of racial disproportionality among female drivers.
Not all DPD units had the same results. The greatest disproportionality was found among the High Enforcement Abatement Team (HEAT), a unit focused on drug, vice and gang violence.
Researchers used the same veil of darkness approach to study traffic data in Raleigh, Fayetteville and Greensboro and no evidence of racial bias was found in those cities.
View the full findings below: