In a Pride Month blow to the estimated 122,000 transgender American teens who are high school athletes, the Supreme Court on Tuesday upheld state bans on transgender girls from participating in girls’ and women’s sports.

The 6-3 ruling reversed a pair of lower court decisions, and was the first time SCOTUS weighed in on the intense national debate about transgender athletes.

While Trump called the decision a “BIG WIN” on social media and West Virginia’s Gov. Patrick Morrisey said future generations of female athletes would benefit from the “certainty, fairness and opportunity,” the Human Rights Campaign called it “deeply disappointing.” The ACLU said it was “a devastating ruling for trans students across the country who simply want the freedom to play with their friends.”

Heather Jackson, the mother of teenage plaintiff Becky Pepper-Jackson, spoke out about the decision in a piece for USA Today. She said that, despite it, “Becky would be a winner because she has shown all of us how to love, accept and be ourselves no matter the outcome.”

She wrote that “Becky’s smile is … her most powerful response to the cruelty coming from the sidelines. She keeps her head high. She cheers everyone on. That is what a good teammate looks like. That is what a winner looks like.

“When I watch from the bleachers, that’s who I see,” she added. “A teenager with an extraordinary capacity for kindness and perseverance. A kid who loves her team, her coaches and her school, and who never asked to be in this fight.”

Below, an explainer on what happened and what the SCOTUS decision means.

What did SCOTUS rule on?

The ruling in a pair of cases upholds laws in two states, West Virginia and Idaho — as well as in 25 other states that also block transgender girls from playing on teams that match their gender identity.

In the Idaho case, trans college student Lindsey Hecox had been barred by state law from trying out for the Boise State University varsity women’s track team. She challenged the ban by saying it violated her right to equal protection of the law under the Constitution.

The West Virginia case involved transgender middle school student Pepper-Jackson, who switched from cross-country to shot put in sixth grade and began winning ribbons by eighth. That’s when the state appealed to the Supreme Court, and West Virginia Attorney General John McCuskey told NPR, “Biological differences between men and women matter on the field.”

Advocates for transgender athletes are pointing out that the ruling does not affect trans athletes’ ability to compete in girls’ events in states that don’t have such bans. “Will the President and others who are trying to write trans people out of public life claim that this decision strengthens their arguments in the sports context? Probably,” Amanda Goad with the ACLU of Southern California said in an email to the New York Times. “But that’s explicitly NOT what the opinion says or does.”

What Were the Arguments?

Those who support a ban on transgender athletes say such laws are needed to prevent athletes born biologically male from having an unfair physical advantage in women’s sports.

Those against the transgender bans say that such laws discriminate based on sex, in violation of both federal Title IX law and the Constitution’s guarantee to equal protection of the law.

But the Supreme Court ruled that because Title IX explicitly allows sex-segregated athletic teams, states can limit team players to their sex at birth.

Both sides have vowed to continue the fight, with supporters of the ruling vowing to broaden it.

“Blue states with boys on girls’ podiums … you’re next,’’ Kristen Waggoner, the president of the Alliance Defending Freedom, which defended the laws barring trans athletes in Idaho and West Virginia, wrote on Instagram.

Director of the Nonbinary and Transgender Rights Project at Lambda Legal Sasha Buchert, meanwhile, said on social, “This ruling is deeply harmful for transgender women and girls who only asked for the ability to participate in sports with their peers. We will not be deterred and will continue to fight back to secure the equal participation that all youth, including transgender youth, deserve.”

And, said National Center for LGBTQ Rights’ Legal Director Shannon Minter, “This is a setback, not the final word.”