Steven Camarota, director of the Center for Immigration Studies in Washington, said valid conclusions are hard to make because data provided by Sheriff Joe Arpaio does not include any socioeconomic information, The Arizona Republic reported.
Camarota was retained by the Maricopa County Sheriff's Office in 2010 to determine if bias was present in deputies' interactions with Latino residents. He testified for 2 1/2 hours under defense questioning in a federal civil rights suit against Arpaio's agency.
Camarota added that 30 percent of the stops he examined did not have any names attached to them, further complicating his analysis.
He took issue with testimony by an expert witness for plaintiffs that Hispanics were more likely to get stopped by deputies, the report said. He said the expert disregarded traffic stops resulting in arrests for crimes such as drunken driving, drug possession and driving with a suspended license.
Lawyers for the plaintiffs, a group of Latino citizens, rested their case earlier Tuesday.
The trial is expected to end Thursday.
The judge has not indicated when he will rule.
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