“The way Louisiana has funded the criminal justice system is to try and provide as many user fees as possible to finance it,” said Rafael Goyeneche, the president of the Metropolitan Crime Commission, a New Orleans-based watchdog group. Pointing out that the fees can sometimes be larger than the actual criminal fine, Mr. Goyeneche said that the system created a clear incentive for high fees, and even for conviction. “These Louisiana laws violate the Constitution,” he said.

While more than eight out of 10 defendants in the criminal court here qualify as indigent, the suit alleges that fees are often imposed without hearings to consider the defendants’ ability to pay. This was the case with all of the named plaintiffs in the suit. One of the plaintiffs is a man kept in jail for weeks for unpaid debts despite his protests that he had a job waiting that would have allowed him to earn the money. Another man spent six days in jail on a warrant issued in error, while a third was told by a collections officer to pay double every time he was late with a payment.

“It’s a failing system, and they know it’s a failing system,” said the third man, Reynaud Variste, 26, who was arrested in a police raid at his home one morning this year after he had fallen a few weeks behind in payments connected to a two-year-old illegal possession case.

The fees can begin accumulating immediately after an arrest, as soon as a bond is set. While a federal court in 1991 struck down a state law allowing New Orleans judges to take a percentage of each bond, a subsequent law mostly reinstituted this arrangement — but split up the percentage among the other actors in the criminal justice system.

“Obviously, there is a legal issue there,” said Calvin Johnson, a retired chief judge of the Orleans Parish Criminal District Court. But he said those most likely to protest the arrangement — the public defenders, the prosecutors and the sheriffs — all benefit from it. “We got all of them in the mix,” he said, “and so they had no interest in saying, ‘Judges, y’all can’t do it.’”

Mr. Johnson has become an outspoken critic of this structure, but said it remained a grudging necessity in the absence of any other funding. “We as a citizenry, we don’t want to pay for the criminal system because we think it only impacts criminals,” he said.

The part of the system here that has drawn the most public outrage recently has been the judicial expense fund. This fund is intended to cover costs — from coffee to office supplies to the salaries of court support staff — unmet by state and local dollars. It is fed by assessments imposed on individual defendants at the judge’s discretion, and can reach $2,000 per felony charge.