Ultimate Fighting Championship fighters suing the mixed martial arts organization for wage suppression are accusing it in Nevada federal court of withholding a large amount of evidence key to the UFC's bid to force their antitrust claims into arbitration.

The fighters, led by Kajan Johnson, argued in a brief filed Saturday that the discovery in their lawsuit, as well as in a related antitrust class action filed by professional MMA fighter Mikhail Cirkunovs, will likely reveal that the arbitration clauses of defendants Zuffa LLC, TKO Operating Co. LLC dba UFC, and Endeavor Group Holdings Inc. are unenforceable.

The court has previously found that the fighters' monopsonization claim against Zuffa and the UFC bears directly on the fairness of Zuffa's arbitration clauses, the brief said. A monopsony is a market condition similar to a monopoly, but dominated by a single buyer rather than a single seller.

According to the brief, U.S. District Judge Richard F. Boulware said in an August minute order that additional discovery would help him determine whether Zuffa and UFC's arbitration agreements or class-action waivers are procedurally unconscionable under Nevada law and the Federal Arbitration Act because of unequal bargaining power.

"In the [Oct. 30] hearing precipitating this filing, the court stated: 'I do think and do find that the evidence related to monopsonization is relevant for the inquiry as it relates to the arbitration agreement, particularly on the issue of unconscionability,'" the brief said.

Also, the fighters argued, Zuffa and the UFC's August motion to compel arbitration in Cirkunovs' case can't be adjudicated because the state of discovery at this point is "severely lacking."

"Virtually non-existent from defendants' productions are every type of document and all the information necessary to adjudicate defendants' motion to compel arbitration as well as the merits of this case generally," the brief said. "Defendants (i) have not collected documents from all the appropriate sources; (ii) have used inadequate and inappropriate search and culling methodologies and processes to review the documents collected; (iii) appear to have failed to preserve (and spoliated) critical documents and communications; and (iv) repeatedly failed to fully comply with this court's orders."

Judge Boulware's August order also rejected the UFC's motion seeking to deny class certification for the Johnson fighters, saying the request is premature.

Zuffa and the UFC had argued that the Johnson plaintiffs cannot be class representatives because they did not sign the arbitration agreements or class action waivers that the majority of fighters in the proposed class have signed.

"But plaintiffs are currently challenging these provisions as unconscionable," Judge Boulware wrote. "Were the court to agree, Zuffa's objection would be moot."

Zuffa had moved in April to deny class certification in the Johnson suit. It said it added arbitration clauses and class action waivers to its fighter contracts after 2017, which is the end point for the class in a similar, settled lawsuit filed and led by fighter Cung Le in 2014.

However, the court said it retains broad discretion when handling the class certification process, especially when it comes to discovery.

"At a minimum, additional discovery will help the court determine whether these provisions are procedurally unconscionable under Nevada law and, accordingly, the Federal Arbitration Act," Judge Boulware wrote in his August order.

Because most of the fighters in the Johnson lawsuit signed agreements that said they would resolve disputes through arbitration, the UFC has said they have waived their right to participate in a class action, citing Ninth Circuit precedent in Lawson v. Grubhub .

The lawsuits accuse Zuffa and the UFC of running an anticompetitive scheme to maintain monopoly and monopsony power in the market for professional mixed martial arts bouts and fighters. The defendants have suppressed competition, leading to anticompetitive wages and other antitrust injuries and damages, the suits claim.

Counsel for the fighters declined to comment Wednesday. Counsel for the UFC did not immediately respond to a request for comment.

The fighters are represented by Michael Dell'Angelo, Eric L. Cramer, Patrick F. Madden, Robert C. Maysey, Kyla Gibboney and Joshua P. Davis of Berger Montague, Michael J. Gayan of Kemp Jones LLP, Joseph R. Saveri, Kevin E. Rayhill and Christopher Young of the Joseph Saveri Law Firm LLP, Richard A. Koffman, Benjamin D. Brown and Daniel H. Silverman of Cohen Milstein Sellers & Toll PLLC and W. Joseph Bruckner, Kyle J. Pozan and Brian D. Clark of Lockridge Grindal Nauen PLLP.

Zuffa, TKO and Endeavor are represented by Christopher S. Yates, Aaron T. Chiu, Sean M. Berkowitz, Laura R. Washington and Joseph Axelrad of Latham & Watkins LLP, William A. Isaacson, Jessica E. Phillips and Agbeko Petty of Dunn Isaacson Rhee LLP and Donald J. Campbell and J. Colby Williams of Campbell & Williams.

The cases are Johnson et al. v. Zuffa LLC dba Ultimate Fighting Championship and UFC et al., case number 2:21-cv-01189, and Cirkunovs v. Zuffa LLC et al., case number 2:25-cv-00914, both in the U.S. District Court for the District of Nevada.