Labaton Sucharow has moved for a federal judge reviewing its billing records to recuse himself from a securities class action settlement, citing a “serious conflict” raised by statements from the judge, which the firm said implied that the New York law firm was engaged in public corruption.

According to the motion, remarks made by U.S. District Judge Mark Wolf of the District of Massachusetts at a May 30 hearing raised “a legitimate concern as to whether Labaton will receive a truly impartial review.”

The statements at the center of the dispute were made during an exchange between Wolf and George Hopkins, the executive director of the lead plaintiff, the Arkansas Teachers Retirement Fund. According to the motion, Wolf's decision to force Hopkins, to testify “gives rise to an inference that the court is already predisposed toward finding misconduct on the part of Labaton.”

The motion, originally filed on June 8, was one of several documents unsealed by Wolf on Friday. The unsealed documents relate to an investigation begun a year ago into allegations of potential overbilling in a $75 million fee request made by Labaton Sucharow and two other law firms, San Francisco's Lieff Cabraser Heimann & Bernstein and the Thornton Law Firm in Boston. Those three firms have served as lead plaintiffs counsel in cases against State Street Corp. To spearhead the overbilling probe, Wolf brought in a special master, Gerald Rosen, a retired federal chief judge from the Eastern District of Michigan, who filed his 377-page report on May 14 under seal.

Labaton Sucharow's recusal motion also indicated that class counsel would be seeking an accounting of the $3.8 million they have spent to fund the special master's report.

“That millions of dollars paid by customer class counsel have been expended on the master's investigation without a suggestion of, or a shred of evidence to support, public corruption is telling,” the motion continues.

Wolf appears to be focused on the report's finding of an undisclosed payment that went to a lawyer for a referral. According to a transcript of the May 30 hearing, Wolf said he could end up returning a “significant amount of money” to class members. In the motion unsealed on Friday, Labaton Sucharow indicated in a footnote that the special master has proposed a $4.1 million cut, the “same amount as the fee paid to the referring firm.”

Wolf has set a closed hearing for June 22.

The unsealed documents and transcript of last month's hearing unveiled some of the report's findings. Lawyers are still fighting over what should be redacted before a public version gets released.

Wolf had ordered Hopkins to show up in person to address whether, given the findings of the report, the judge should replace class counsel, and the lead plaintiff, in light of a potential conflict of interest. Hopkins, in a June 6 affidavit, said he had retained outside counsel to handle questions relating to the special master's report but insisted that the Arkansas pension fund could continue to adequately represent the class.

Hopkins' counsel, Thomas Hoopes of Boston's LibbyHoopes, declined to comment.

At the May 30 hearing, according to a transcript, the judge's primary focus was on having Hopkins explain the “origins and evolution” of the Arkansas pension fund's relationship with New York-based Labaton Sucharow. He also wanted to know more about what he called the “referral fees.”

Wolf's focus was on a retired state legislator named Steve Faris. In particular, he wanted to know how much Hopkins had talked to Faris about the law firms handling of the pension fund's class actions.

“Did he ever tell you that he had a role in introducing Labaton to Arkansas Teacher?” Wolf asked according to a transcript of the hearing.

“No, he never told me that, ” Hopkins answered, referring to Faris.

Later in the hearing, Hopkins told the judge in sworn testimony: “I have never asked a law firm to hire some attorney. I have never asked a law firm to make a political contribution.”

“I chose the law firm that would proceed in this case, because I interviewed several,” he added.

According to the transcript of the sidebar discussion, Labaton's attorney, Joan Lukey, of Boston's Choate Hall & Stewart, said she was shocked at the judge's remarks at the hearing.

“You're suggesting public corruption,” she replied. “Honestly, your honor, I am appalled that that was even said.”

Labaton Sucharow, in a statement, called the judge's suggestion that a payment may have led to the firm's hiring as “baseless.” Further, the firm wrote, “there is no mention of any such influence payment in the special master's exhaustive report, which remains under seal” and “not a single finding suggesting that attorneys' fees awarded by the court were used to pay elected or other officials.”