Thomas filed the suit in U.S. District Court, alleging that the separate courts for defendants who speak Spanish or American Indian languages are illegal.
"Maricopa County's race-based courts are unconstitutional and must be ended," Thomas said in a statement. "Our criminal justice system must remain colorblind. I am obliged by my oath of office to challenge them through all lawful means until this day comes."
Presiding Superior Court Judge Barbara Rodriquez Mundell has defended the specialized DUI courts, emphasizing that they were designed to reduce drunken-driving deaths and accidents by helping two large minority groups through alcohol recovery and education.
Mundell said the special DUI courts do not conduct trials or issue sentences; they oversee post-conviction conduct of volunteer participants who are treated no differently than those who attend similar sessions in the English-language program.