When can paying sports fans sue over an event they now consider a fraud? That's what a federal appeals panel weighed Thursday in a case that boxing fans brought over the 2015 match between Floyd Mayweather and Manny Pacquiao, then dubbed the “Fight of the Century.”

The oral arguments before the U.S. Court of Appeals for the Ninth Circuit intertwined the unpredictability of sports with how much paying fans needed to know about an athlete's injuries. Plaintiffs' lawyer Hart Robinovitch is attempting to reverse dismissal of dozens of class actions brought by fans who paid $89.95 to watch the match on HBO pay-per-view but were unaware that Pacquiao, the losing boxer, had a pre-existing torn rotator cuff before stepping into the ring at the MGM Grand Hotel in Las Vegas.

Panelist Jacqueline Nguyen appeared to struggle with how far consumers could go in forcing athletes to disclose injuries, which are common in sports.

“Where do you draw the line?” she said. “You can't psyche out your opponents by saying, 'I'm feeling great. I'm going to win'?”

Attorneys for the boxers, who made more than $100 million from the fight, said the case was about disappointed fans, not fraud. They cited the boxing match in which Mike Tyson bit off Evander Holyfield's ear, or when the New England Patriots videotaped the sideline signals of the New York Jets. In both cases, courts ruled against fans who had sued.

In court, Pacquiao's attorney, Daniel Petrocelli, also mentioned the dismissal of a lawsuit over a referee's “no call” that critics contend kept the New Orleans Saints out of this year's Super Bowl.

Reversing dismissal of this case, he said, would “open the floodgates.”

“We're not talking about buying a hammer made in the U.S.A. when it turns out it's not made in the U.S.A.,” said Petrocelli, a partner at O'Melveny & Myers in Los Angeles. “We're talking about buying uncertainty, unpredictability, drama, controversy, things that people can argue about all the time, things that relieve us of the daily routine and rigor of our lives. That's what makes sports so addictive to people.”

Aaron Swerdlow, of Los Angeles-based Weinberg Gonser, who is following the case, agreed that a Ninth Circuit decision to revive the case could put all kinds of sporting events at risk—even gambling.

“The concern with this case in the sports industry is if this is successful in any way, it opens sporting events to lawsuits,” he said.

More than 40 class actions were filed, later coordinated into multidistrict litigation, following the 2015 boxing match. In 2017, U.S. District Judge R. Gary Klausner in Los Angeles dismissed the cases, concluding that fans got what they paid for: the right to view a match between Pacquiao and Mayweather. “Plaintiffs had no legally protected interest or right to see an exciting fight, a fight between two totally healthy and fully prepared boxers, or a fight that lived up to the significant pre-fight hype,” he wrote.

Nguyen and Ronald Gilman, a judge on the U.S. Court of Appeals for the Sixth Circuit, sitting by designation, heard arguments Thursday. Raymond Fisher was on the panel but absent for the hearing.

Robinovitch, a partner at Zimmerman Reed in Scottsdale, Arizona, said the line was drawn when the boxers and their promoters induced fans to pay money to watch an event without knowledge of a material fact; the shoulder injury. He called the match a “unique event,” unlike a routine football or basketball game.

“When you go see the Lakers here, you don't have a guarantee that LeBron James is going to play the whole game,” he said. “That is the uncertainty of sports. What you have here is something far different. This was a material fact, a known fact, a verifiable fact, that was known well before they sold the tickets.”

He relied on a 1999 decision by the California Court of Appeal allowing season ticket holders of the Los Angeles Rams to pursue fraud claims following the team's decision to move to St. Louis after the 1994 season. (The team moved back to Los Angeles in 2016). In particular, Robinovitch cited a footnote in the ruling that said, “had the Rams lied that [the team] had signed a superstar quarterback, we see no reason why ticket buyers who relied on this fact would not be entitled to rescission at least.”

He pushed back against Klausner's finding that cases in which sports fans were allowed to sue involved misrepresentations made about objective business or financial factors, not about the nature of the competition or the quality of the athletes' performance.

Petrocelli latched onto Klausner's analysis that the purchase of tickets was like a “license” to view a sporting event—nothing more, nothing less.

“Whenever it relates to the actual performance or quality or strategy or competitiveness of the event, that's where the courts have drawn the line,” he told the panel. “Are the Patriots supposed to disclose when Tom Brady has a severe migraine headache before a game?”

Moreover, should opponents have to disclose such injuries, even if they know about them? That's the question raised by Mark Tratos, a shareholder at Greenberg Traurig in Las Vegas, who argued Thursday for Mayweather and his promotion company, both defendants in the case.

“This court should not assert a new duty on opponents in sporting contests that has never before been recognized and should not be recognized now,” he told the panel.