Labor turmoil in the world of mixed martial arts.

Last May, a group of some of the most fearsome fighters in the world gathered in a hotel room at the Red Rock Casino Resort & Spa in Las Vegas. Initially, only three or four showed up for the meeting; but eventually 19 brawny bodies packed into the room. The fighters were attending a two-day summit hosted by Ultimate Fighting Championship (UFC), a promotion outfit that, in recent years, has become nearly synonymous with mixed-martial-arts fighting—an often bloody spectacle in which competitors combine elements of Brazilian jiu-jitsu, boxing, and wrestling.

This particular meeting, however, wasn’t on the summit’s official agenda. It had been convened by Robert Maysey—a Scottsdale, Arizona, lawyer and mixed-martial-arts enthusiast, who was trying to enlist support for a fighters’ association. He projected PowerPoint slides onto a screen, estimating UFC’s revenue and laying out the advantages to collective bargaining. The fighters, he recalls, were intrigued. “They all would have signed right then and there,” he told me when we spoke recently.

But then, one of the star fighters stood up. “Rob, I’d love to, but they’ve got me by the balls,” he said, referring to UFC. “They’ve got half my pay in bonuses.” Others worried that UFC would blackball them if they were to organize. One by one, the fighters filtered out. Maysey tried to follow up later on, but they all eventually stopped returning his calls.

For a long time, mixed martial arts—or MMA, as it’s known—resided on the fringes of American culture. And the sport remains illegal in Connecticut and New York. (A bid to overturn the New York ban failed in the state assembly earlier this month.) In the rest of the country, however, MMA is no longer a marginal enterprise. UFC—having in recent years bought up most of its competitor organizations and established control over 80 to 90 percent of the mixed-martial-arts market—is now worth more than a billion dollars. Last year, the company signed a seven-year TV deal with Fox worth a reported $100 million annually. The rules governing MMA have changed, too: Where once only eye-gouging and biting were officially off limits, UFC now bans groin attacks, heel kicks to the kidney, and throat strikes. Mixed martial arts, in other words, appears on its way to becoming a semi-legitimate sport. But one thing is still largely missing: labor protections for fighters.

ROBERT MAYSEY is 37 and has the sturdy build of a former college athlete. Growing up playing baseball and football, he initially dismissed MMA as a “blood sport that exploits underprivileged people,” but his opinion changed after he watched a UFC competition in 1996. Witnessing the event inspired him to join a small jiu-jitsu club at Cornell when he enrolled in the law school that fall, and he quickly became hooked, keeping up with his training even after he graduated and moved to Los Angeles.