Former and current mixed martial artists sued the Ultimate Fighting Championship league on Tuesday, alleging the business has a monopoly on the professional fighting market and limits the potential earnings of its athletes.
The suit, filed in federal court in California by one current and two former fighters, aims to establish a class of fighters who have performed at any UFC event held or broadcast in the United States.
"Through a series of anticompetitive, illicit, and exclusionary acts, the UFC has illegally acquired, enhanced, and maintained dominant positions in the markets," the lawsuit said. "As a result of this scheme, UFC Fighters are paid a fraction of what they would earn in a competitive marketplace."
The complaint estimated that UFC's parent company, Zuffa LLC, which is also named as a defendant, currently sees annual revenues exceeding US$500 million (S$651 million).
The UFC said in a statement that it was aware of the suit, but it had neither been served nor reviewed the filing.
"The UFC will vigorously defend itself and its business practices," the statement said.
Plaintiff Cung Le, a middleweight in the league whose suspension over testing positive for outsize levels of human growth hormone was rescinded in October, told ESPN, "They control our career, and that's a choice we as fighters should have. And we don't have that choice."
Former fighters Jon Fitch and Nate Quarry are also plaintiffs in the case.
The complaint said that the UFC also has intimidated and threatened fighters that attempt to work with rival firms or who criticise the league.
The complaint said that in one instance, UFC fighter B.J. Penn told the league he planned to sign with another promotion company for higher pay after winning a welterweight title fight.
UFC President Dana White then allegedly called Penn, saying, "You'll never fight in the UFC again! You're finished. You're scorched earth, motherf***er."
The suit seeks money damages, including additional payment fighters could have received from other mixed martial arts businesses, and an injunction against the alleged anticompetitive actions of the UFC.