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Last fall, under scrutiny for its decision years earlier to stop tracking the race of drivers who get pulled over, the Pennsylvania State Police pointed to a series of independent studies that officials said proved there was no consistent bias in the way troopers did their jobs.

But a review of those studies reveals a far more nuanced picture of what was actually occurring, raising new questions about why the data collection was halted and how troopers are trained to prevent people of certain races from being unfairly targeted.

The findings, contained in 2,000 pages of research produced by the University of Cincinnati and obtained by Spotlight PA under the state public records law, indicated no consistent evidence over the study period that troopers stopped drivers, issued citations or made arrests based on race.

But they did reveal a persistent problem after stops had occurred: Year after year, according to the reports, troopers were roughly two to three times more likely to search black or Hispanic drivers than white drivers. At the same time, the researchers found, troopers were far less likely to find contraband on black and Hispanic drivers compared to white drivers.

“It’s very concerning,” said Chris Burbank, vice president of the Center for Policing Equity, an organization that helps police departments prevent racial profiling. “But not surprising.”

In 2002, following scandals in New Jersey over racial profiling by state troopers, the Pennsylvania State Police began collecting data from its hundreds of thousands of traffic stops each year and sending it to the University of Cincinnati for analysis.

A decade later, without making an announcement and for reasons that are still unclear, the agency ended its partnership with the university and stopped collecting the data. In September of last year, in response to questions from Spotlight PA about why it discontinued the monitoring, the State Police said the researchers had concluded there was no evidence that troopers “were conducting traffic stops based on drivers’ demographics.”

The agency, however, made no mention of the disparities found during searches. Nor did it mention that researchers noted unexplained increases in stop and arrest rates of black drivers by certain stations in several years. In the final study, analyzing 2010 traffic stops, the researchers noted an unusual department-wide rise in stops of black drivers, although, again, they said they could not explain what was causing the increase.

Because the data collection ended, it’s impossible to know what has since occurred.

Robin Engel, a University of Cincinnati criminal justice professor who led the research, did not respond to repeated calls and emails seeking an interview.

The Pennsylvania State Police said it stood by its September statements that Engel’s research showed no evidence its troopers conducted traffic stops based on race or ethnicity. Asked why it ended its program given the disparities in search rates, Lt. Col. Scott Price reiterated that the decision was made by executive staff at the time and that the full rationale remains unknown.

“We have not found documentation that points to a single reason that drove the decision,” Price said in a statement.

In the final years of data analysis, researchers recommended the State Police conduct a more detailed review to determine which stations had the greatest racial disparities in search rates and then interview the commanders there to better understand why those disparities might exist. Price said he didn’t know what, if anything, was done in response to the recommendations.

He reiterated that the State Police would resume collecting race data this year, and that it is currently seeking a contractor to analyze that data, just as the University of Cincinnati had done in the past. The agency first announced its decision to resume data collection last year in response to inquiries from Spotlight PA.

A survey at the time found the State Police was one of only 11 statewide law enforcement agencies in the U.S. — and by far the largest — that did not collect race data during stops.

In an interview earlier this month on WITF, Central Pennsylvania’s public radio station, the president of the Pennsylvania State Troopers Association, David Kennedy, also pointed to the University of Cincinnati research as proof troopers don’t pull drivers over based on their race.

“The overwhelming numbers were in the Pennsylvania State Police’s favor,” Kennedy said. “We do not pull people over because of their color.”

When later asked by Spotlight PA about the disparities in search rates, Kennedy issued a statement saying, “Troopers go to work everyday ready to sacrifice their lives for their fellow Pennsylvanians.”

“They do so without regard to race or ethnicity,” Kennedy said. “We recognize that we will always have our critics, but that’s part of the job. We won’t change our focus on keeping Pennsylvania safe.”

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Burbank, of the Center for Policing Equity, said the search rate disparities were alarming because it meant troopers were potentially taking action based on little more than the color of a driver’s skin. Searches like those are not only unconstitutional but self-defeating: they erode the trust that black and Hispanic drivers have in the police, he said, meaning in the future those people might be less likely to report crimes or provide information to officers to solve cases.

“That cost to society is significant,” said Burbank, a former police chief in Salt Lake City, Utah.

Some question more generally whether the State Police has been too slow to improve bias-based training and awareness.

Currently, cadets are presented with information within the first few weeks of academy training on the importance of non-biased policing and how to be aware of implicit biases. They do not receive additional anti-bias training throughout their career, though Price said the State Police is now developing such a continuing education plan.

Witold Walczak, the legal director for the ACLU of Pennsylvania, said it was irresponsible that the nation’s third-largest statewide law enforcement agency was only now developing that curriculum and resuming its analysis of traffic stops.

“To say, ‘we are not going to study this,’ or take affirmative measures to combat it is putting your head in the sand,” Walczak said of State Police officials.