This piece is part of a series on Obama’s legacy that The Huffington Post will be publishing over the next week.

When the United States Women’s National Team visited the White House in October 2015 to celebrate winning the Women’s World Cup, President Barack Obama didn’t mince words when sharing his excitement.

“This team taught all of America’s children that ‘playing like a girl’ means you’re a badass,” he said.

He paused for a second.

“Perhaps I shouldn’t have used that phrase.”

The crowd laughed.

Left unsaid, though, was that the overwhelming dominance of American female athletes in international competitions during Obama’s two terms represented a major public policy victory for the United States, which more than four decades earlier had enshrined equal opportunity for girls and women in sports into federal law.

Obama is not responsible for creating Title IX, the 1972 law meant to guarantee women and girls equal access to athletics and education. But the president has aggressively celebrated, enforced and expanded Title IX’s reach on issues from gender equity in sports to campus sexual assault to the rights of transgender students and athletes.

Now, as President-elect Donald Trump sets out to reshape federal education policy, the question is whether that legacy can remain intact.

Portland Press Herald via Getty Images There were more than 3,600 Title IX complaints alleging gender disparities in scholastic sports during the 2013-14 fiscal year.

A Reversal Of Bush-Era Policy

Although Title IX itself does not explicitly mention sports, it is most commonly associated with gender equality on the athletic field. And almost immediately after Obama took office, his administration set about reshaping how the law applied to female athletes.

In 2005, President George W. Bush’s Department of Education walked back decades of Title IX practices by changing the rules for how to determine whether schools had violated female students’ rights to equal opportunity. The Bush administration’s move was seen as a setback for women and girls, who still faced massive gaps in access to sports at the primary and secondary school level. Activists pressured Obama and then-Education Secretary Arne Duncan to take action.

The Education Department reversed the Bush administration’s guidance in 2010, reinstating earlier standards that increased the burden on schools to demonstrate their compliance with the law. Complaints under Title IX drastically increased in the following years: In the 2013-14 fiscal year, the department’s Office of Civil Rights received more than 3,600 official complaints alleging disparities in athletic opportunities — nearly triple the number that had been filed in the four years prior.

Activists at the time said the rise in complaints were due at least in part to increased awareness about the law and the growing expectation that women and girls deserve equal footing on the field.

USA Today Sports / Reuters Tampa Bay Buccaneers quarterback Jameis Winston was accused of sexual assault while he played for Florida State University -- a case that raised broader awareness about the Obama administration's move to use Title IX to combat campus sexual assault.

A ‘Historic’ Move Against Campus Sexual Assault

A year later, an even bigger change — one that could become the defining legacy of how Obama and Vice President Joe Biden approached Title IX — arrived when the administration took on an issue activists and students had pressed them on for years: campus sexual assault.

Federal officials had previously released recommendations on how to handle sexual assault and violence complaints under Title IX. But in 2011, the Office of Civil Rights issued what’s called a “Dear Colleague” letter — a means of outlining procedures and official departmental guidance under the law — that told school administrators at the collegiate and K-12 level that they were responsible for protecting women from sexual violence and outlined specific rules and procedures for how to handle claims of assault.

“This was historic,” said Valerie Jarrett, a senior adviser to the president who spearheaded much of the administration’s gender equity policy moves. “While Title IX had always protected students from sexual harassment and assault, this was the first time any federal administration called sexual violence a civil rights issue.”

That change has had tangible effects, especially when coupled with awareness campaigns Biden and student activists launched in subsequent years: The Office of Civil Rights is currently investigating more than 400 sexual assault complaints at colleges and schools, Jarrett said. Those include complaints at some of America’s most prestigious universities — including Harvard, Yale and Stanford — and in school districts in some of its largest cities, including the nation’s capital.

Several of the most high-profile cases involving Title IX and sexual assault came from the world of college sports. None, perhaps, made bigger news than the case of former Florida State quarterback Jameis Winston, who was accused of rape by a female student in 2012. Winston wasn’t charged — Florida State settled a Title IX lawsuit with the accuser in January 2016, and Winston and his accuser ultimately settled lawsuits against each other in December.

But his case became a national example of the myriad issues around sexual assault on college campuses. It had the effect of broadening the impact of the Obama administration’s efforts to change the way such cases are handled, said Scott Lewis, a partner at the NCHERM Group, which advises schools on Title IX compliance.

“The Winston case, I think, took it to the broader audience in a fashion that had not been introduced to them before,” Lewis said. “That broadened the audience. Now you had ESPN talking about it in a different way [as well as] other people who before weren’t as open to that concept having more discussions about how schools should be doing this.”

Mike Segar / Reuters Betsy DeVos, President-elect Donald Trump's pick to head the Department of Education, has visions of reshaping education policy but has said little about her views on Title IX.

‘Concern’ For The Trump Era

The Obama administration took another major action on Title IX in May, when the Education and Justice departments reminded schools that the law guaranteed equal treatment for transgender students — something that will inevitably spill over into athletics, given the controversy over the ability of those students to access the bathrooms and locker rooms that match their gender identity.

However, activists and experts are worried that the Trump administration could roll back Obama’s expansive actions.

Conservatives have already opposed the inclusion of transgender students under Title IX. The issue could soon be decided in court, after a federal judge granted a preliminary injunction requested by Texas and other states.

There have also been concerns ― including from universities and legal scholars ― that the Obama administration applied Title IX to campus sexual assault and harassment issues in ways that hurt due process rights of accused students or lead to overzealous investigations.

Betsy DeVos, Trump’s pick to head the Department of Education, supports major reforms for public education. And although her past suggests she will oppose the Obama administration’s inclusion of transgender students in Title IX, she has said little about her approach.

There’s a lot of understandable anxiety based on statements by the campaign and nominations that have been announced. Neena Chaudhry, director of education at the National Women's Law Center

“Obviously we’re concerned there will be a rollback in enforcement,” said Neena Chaudhry, director of education and senior counsel at the National Women’s Law Center in Washington.

“There’s a lot of understandable anxiety based on statements by the campaign and nominations that have been announced,” she said. “We’ve already seen an uptick in harassment and violence even since November, and I think it will be very important for the incoming administration to ... continue to vigorously enforce civil rights law.”

But Chaudhry and others also see reasons to believe that big, swift changes might not come — especially when it comes to addressing campus sexual assault.

There’s bipartisan support for Senate legislation that could force sweeping changes in how colleges handle sexual assault cases. And schools have begun to take action on their own. Florida State, for example, argued that it undertook major efforts to reshape its approach to sexual assault cases in the wake of the Winston case, and Lewis said the rash of investigations and complaints over the last five years have begun to shift attitudes on campuses across the country. Schools now believe they have the responsibility to address these issues, and those attitudes won’t be easy to change.

At least on sexual assault issues, the Obama administration’s Title IX legacy is “pretty well-established in the fact that schools are really changing the way they address these issues, arguably in a fashion that should have been changed years ago,” Lewis said. “There’s an increase in reporting of incidents, an increase in adjudication, and an increase in accountability. I think their legacy is that schools are starting to realize that they have to do this better.”

JIM WATSON via Getty Images Ayla Ludlow visited the White House after writing a letter to President Barack Obama about the U.S. Women's National Team's performance at the 2015 Women's World Cup.

There is similar momentum in sports. During the Obama years, women have ascended to previously inaccessible roles and set milestones in the Olympics, Major League Baseball, the NFL, the NBA and the sports media.

When the USWNT visited the White House, a 13-year-old girl named Ayla Ludlow introduced the president.

That summer, Ayla’s brother had walked into the room where she was watching the Women’s World Cup.

“Ayla,” she says he said, “boys are so much better than girls at soccer.”

“It makes me mad that people do not treat girls equally,” Ayla wrote in a letter to the Obamas.

“Plus,” she wrote, “a lot of girls are better at sports than boys.”