(PARIS) -- The U.S. women's national team beat the Netherlands on Sunday to defend their status as champions in the World Cup.
When they get back home, they've got a whole different battle awaiting them -- their legal fight for equal pay and treatment from the United States Soccer Federation.
In March, the 28 members of the 2015 World Cup-winning team -- including stars Alex Morgan, Megan Rapinoe and Carli Lloyd, who are still competing on the national team -- filed a lawsuit against the U.S. Soccer Federation alleging gender discrimination in their treatment versus how the governing body treats the men's team.
"The U.S. women's soccer team does not need to be the best in the world in order to earn equal pay. The point of non-discrimination law is that employees doing similar work should be paid equally," Suzanne B. Goldberg, director of the Center for Gender & Sexuality Law at the Columbia Law School, told ABC News.
The lawsuit cites not just pay, but also the denial of "at least equal playing, training, and travel conditions; equal promotion of their games; equal support and development for their games; and other terms and conditions of employment."
In May, U.S. Soccer fired back in a response, saying, "any alleged pay differential" is due to "differences in the aggregate revenue generated by the different teams" and other factors, including "different obligations" and being "compensated in fundamentally different ways."
Late last month, a spokesperson from U.S. Soccer confirmed to ABC News that the women's team and the federation tentatively agreed to mediation after the World Cup.
"The women are paid under a different structure than the men, which they preferred and specifically negotiated for, but that doesn't mean they are compensated less by U.S. Soccer," a U.S. Soccer spokesperson told ABC News.
The federation has said the differences come from differences in contracts. The men fall under a "pay-for-play" structure and are "only paid for individual match appearances" on tournament or tournament-qualifying rosters, the organization said.
It argues that male players' compensation cannot be compared to the women "who earn guaranteed salaries and benefits."
When it comes to the actual legal issues at play, the suit points to two federal laws: the Equal Pay Act, which prohibits paying employees unequally based on sex, and Title VII, which prohibits employers discriminating on the basis of sex.
"In any equal pay case, the employee must show that they are doing work that is similar to the men who are being paid more," Goldberg said.
Maya Raghu, director of workplace equality at the National Women's Law Center, told ABC News the equal pay law goes beyond being the best in any competitive area.
"Are you doing substantially equal work? And if you are, then you should be paid the same as your male counterparts unless there's a justification under the law for any disparity," she said.
Those justifications could be due to performance. Some jobs, for example, give bonuses to high-performing employees or pay out commissions based on performance.
Still, Raghu said that in gender discrimination cases, courts should look at why men seem to be higher performing -- such as, for instance, if they are getting more opportunities to meet with bigger clients.
Even so, it's sort of a moot point, Goldberg said, because of the women's superior play.
"In this instance, where the women's team is outplaying the men's team, there is an argument that they should be paid more than their male counterparts," she said.
With the U.S. team's win on Sunday, it was their fourth World Cup title, and their second in a row. The U.S. men did not qualify for the last men's World Cup.
The question of revenue comes up quite frequently in sports gender cases, said Neena Chaudhry, general counsel and senior adviser of education at the NWLC. In school cases, though, "revenue" is more along the lines of game attendance, she said.
Experts say courts should be looking beyond the basic numbers and instead to how organizations are promoting women's sports and what opportunities or resources they are providing.
This, too, may be a moot point, according to recent reports. The Wall Street Journal reported women's soccer games have been out-earning men's games and, more broadly, sales of USWNT soccer jerseys are higher, and viewership on this World Cup has been high.
Some have argued men are paid more because of market forces, and that the male employees are simply in more demand.
But, Chaudhry said, "How much of that is just sort of pretext or justification for continuing to pay men more?"
It's important to note the women are calling not just for equal pay, but for equal treatment, according to Raghu.
"It's not just about the compensation. It's about access to facilities and equipment and the surface they're playing on and sort of their travel and all the many things that come together to make up a working environment," she said.
Ultimately, though, all experts said the significance of this lawsuit goes beyond the individual case.
"[Women and girls] weren't given these opportunities until Title IX passed in 1972, so men have had a very, very long head-start, and there's a lot of work to do to bring women up to the level men have enjoyed for centuries," Chaudhry said.
She added, "It's fundamentally tied to the fact that many people still don't see sports as an arena for women and girls. I know that seems shocking to say in 2019."
This case could impact similar calls for gender equity in other sports -- professionally and in schools -- and beyond, Goldberg added.
"I think we will see reverberations from this case in other sports and other settings," she said. "Just as the #MeToo movement has called attention to the pervasiveness of sexual harassment in the workplace, this prominent lawsuit challenging pay inequity also brings a spotlight to this serious form of discrimination."
"Even regardless of the outcome of the lawsuit," Raghu said, "what they have done for elevating the issue of equal pay in our national consciousness and keeping this conversation going is almost more impactful."
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