Civil rights attorneys have opened a second front in their war on fees at Orleans Parish Criminal District Court.

In a letter sent Thursday, the Lawyers’ Committee for Civil Rights Under Law accuses judges at the court of routinely imposing three categories of fees on poor defendants in violation of state law.

The fees — which are among many that can be imposed by the court — are for court costs and clerk's fees, a fund that provides transcripts for indigents upon appeal, and a sheriff's detention and prison fund.

The letter says the fees are illegal when imposed on indigent defendants, who account for the vast majority of convictions in New Orleans.

Thousands and perhaps tens of thousands of defendants may have been subject to the illegal fees, Kristen Clarke, the president and executive director of the lawyers group, said in a statement. She asked the judges to stop imposing the fees immediately.

“Fines and fees that are imposed without lawful basis have unnecessarily entangled people in Louisiana’s criminal justice system for far too long," she said. "It has got to stop, today."

Criminal District Court Judge Keva Landrum-Johnson, the court’s chief judge, declined to comment on the letter, citing an open federal lawsuit on the issue.

The letter could set the stage for a state lawsuit in addition to a federal lawsuit already challenging New Orleans court fees.

Clarke’s group sued the Criminal District Court judges in federal court in 2015 for relying on fines and fees to pad the local court's budget to the tune of roughly $1 million a year.

U.S. District Judge Sarah Vance handed the group a victory in December. She said the judges have an inherent conflict of interest in assessing fees that support the court's operations.

Thursday’s letter suggests that in addition to the U.S. Constitution, state judges have also run afoul of Louisiana law.

The lawyers group said that in a review of 20 cases from each of the court’s 12 sections, the judges routinely imposed three fees that are supposed to be reserved for “non-indigent” defendants under the law.

The fees amounted to $24,500 spread out among the 240 members of the sample population, or about $100 per defendant. The group did not attempt to put a dollar figure on the total amount of fees it asserts are illegal.

The impact of Vance’s decision is still shaking out in the courthouse at Tulane Avenue and Broad Street, but some judges have stopped imposing fees that they routinely assessed before the lawsuit was filed.

Judge Franz Zibilich said at a July 2014 New Orleans City Council hearing that fines and fees make up about a fourth of the court’s budget. He warned that if judges stop assessing those fees, more money will have to come from another source.

Zibilich estimated that about 95 percent of the city’s criminal defendants cannot afford an attorney.

Follow Matt Sledge on Twitter, @mgsledge.