The judge in Ferguson, Missouri, who is accused of fixing traffic tickets for himself and colleagues while inflicting a punishing regime of fines and fees on the city’s residents, also owes more than $170,000 in unpaid taxes.

Ronald J Brockmeyer, whose court allegedly jailed impoverished defendants unable to pay fines of a few hundred dollars, has a string of outstanding debts to the US government dating back to 2007, according to tax filings obtained by the Guardian from authorities in Missouri.

Brockmeyer, 70, was this week singled out by Department of Justice investigators as being a driving force behind Ferguson’s strategy of using its municipal court to aggressively generate revenues. The policy has been blamed for a breakdown in relations between the city’s overwhelmingly white authorities and residents, two-thirds of whom are African American.

Investigators found Brockmeyer had boasted of creating a range of new court fees, “many of which are widely considered abusive and may be unlawful”. A city councilman opposing the judge’s reappointment was warned “switching judges would/could lead to loss of revenue”.

Brockmeyer, who has been Ferguson’s municipal court judge for 12 years, serves simultaneously as a prosecutor in two nearby cities and as a private attorney. Legal experts said his potentially conflicting interests illustrate a serious problem in the region’s judicial system. Brockmeyer, who reportedly earns $600 per shift as a prosecutor, said last year his dual role benefited defendants. “I see both sides of it,” he said. “I think it’s even better.”

While Brockmeyer owes the US government $172,646 in taxes, his court in Ferguson is at the centre of a class-action federal lawsuit that alleges Ferguson repeatedly “imprisoned a human being solely because the person could not afford to make a monetary payment”.