ST. LOUIS -- Missouri Attorney General Chris Koster on Thursday filed a lawsuit against 13 St. Louis County municipalities, alleging they violate a Missouri law that limits revenue from traffic fines and court fees.

Koster, a Democrat, said reports he requested from municipalities across the suburban county showed a pattern of substandard accounting and excessive collection of revenue from "predatory traffic tickets." Five of the municipalities failed to file annual reports with the state auditor.

Municipal courts in St. Louis County have come under scrutiny since the police killing of Michael Brown in August in Ferguson, which was not among the towns named in the lawsuit. Subsequent protests highlighted the broken relationship between police officers and the communities they serve. Some have complained that aggressive police enforcement of traffic laws disproportionately targets people of color.

Missouri's Macks Creek Law, passed in 1995 and later updated, caps traffic fine revenue at 30 percent of a municipality's budget. Any revenue exceeding the cap is supposed to be given to state schools. But many municipalities are ignoring the law, Koster said.

“The Macks Creek Law was enacted to protect Missourians from predatory traffic tickets. This problem has been felt nowhere more acutely than North St. Louis County,” Koster said.