NEW ORLEANS — Fees and fines collected in a court controlled by the mayor of a Louisiana city provide more than 13 percent of the city’s general fund budget — creating an incentive to increase arrests for minor crimes, a civil rights group said in a federal court lawsuit.

Filed Tuesday by The Roderick and Solange MacArthur Justice Center, the lawsuit claims the city of Gretna collected more than $1.6 million in court fines and fees in the 2014-2015 fiscal year. Another $785,000 was collected through a “Deferred Prosecution Program” that leads to dropping of charges after a probation period — and the payment of a fee.

The MacArthur Center says the system amounts to a conflict of interest for Mayor Belinda Constant, Gretna police, the city’s prosecutor and the magistrate judges who work in the court. The suit alleges that revenue generated by the court provides an incentive for arrest and prosecution of relatively minor crimes that can be prosecuted at the municipal level, rather than in state court.

“In 2000, slightly over 10% of Gretna’s arrests were reported to the FBI under categories of ‘drunkenness,’ ‘disorderly conduct,’ and ‘all other offenses except traffic’ — a catch-all covering various nonviolent misdemeanor offenses,” the suit states. “But by 2014 those categories accounted for over 60% of the total arrests by the Gretna Police Department. During that same time period, the number of Gretna police arrests reported to the FBI for felony crimes of violence and theft markedly declined.”

The lawsuit says the conflict of interest effectively denies defendants in the mayor’s court their constitutional due process rights. It also says poor people are denied due process and equal protection rights because they cannot afford to take part in the deferred prosecution program, and are often faced with driver license suspension for failure to pay fees, fines and court costs that they cannot afford.

City attorney Mark Morgan said in an email Tuesday evening that the city had not had an opportunity to review the allegations. “It appears that the media was provided a copy of a lawsuit prior to the city being provided with the same,” Morgan wrote. He added that assertions that the city had a conflict of interest or violated anyone’s constitutional rights “are categorically denied.”

Two plaintiffs are named in the lawsuit but the MacArthur Center is seeking class action status on behalf of those who have cases pending in the mayor’s court or who, in the last year, were denied participation in the deferred prosecution program because they couldn’t afford it.

The remedies that the lawsuit seeks include a declaration that the court has an unconstitutional conflict of interest. It also seeks refunds of fees collected from those who were kicked out of the deferred prosecution program after falling behind on fees.