PITTSBURGH — Three transgender seniors at a Pennsylvania high school, including the oldest sibling of teen singing star Jackie Evancho, have sued their school district for making them use restrooms corresponding to their biological sex.

The Pine-Richland School District in suburban Pittsburgh wasn’t commenting on the federal lawsuit filed Thursday in response to a school board resolution passed last month requiring students to use such restrooms or unisex facilities. Previously, the district had allowed transgender students to use the restroom corresponding to their “gender identity.”

The district “attempted to erase their identity” and changed the rule due to “misunderstanding, fear and a lack of empathy,” said Omar Gonzalez-Pagan, the New York-based attorney who filed the lawsuit. He works for Lambda Legal, a group that advocates for lesbian, gay, bisexual and transgender individuals,

Two 18-year-old plaintiffs, Juliet Evancho and Elissa Ridenour, were named Jacob and Erik at birth, but now identify as female. The third plaintiff, a 17-year-old, identified only by the initials A.S. now identifies as male. Juliet is now Evancho’s legal name; Ridenour’s remains Erik.

The lawsuit contends they were “designated” male or female on their birth certificates and are being discriminated against by the new policy, which their federal lawsuit seeks to reverse. They’re also seeking unspecified monetary damages, other policies to avoid transgender discrimination and training for administrators.

“The reality is Juliet is a girl, Elissa is a girl and A.S. is a boy,” Gonzalez-Pagan said, noting that the University of Pittsburgh Medical Center has weighed in on the need to allow people to pursue their true gender identity.

Some experts disagree, notably Paul McHugh, the former psychiatrist in chief at Johns Hopkins Hospital, which pioneered sexual reassignment surgery but later discontinued the practice as harmful.

“(P)olicy makers and the media are doing no favors either to the public or the transgendered by treating their confusions as a right in need of defending rather than as a mental disorder that deserves understanding, treatment and prevention,” McHugh originally wrote in a 2014 editorial essay that’s been reprinted in several publications.

Evancho has felt like a girl since a young age, the lawsuit said, preferring to play with dolls, using makeup and wearing wigs and dresses at home. Evancho didn’t publicly identify as a girl until last year.

As an adolescent, Juliet sang a duet on an album by sister Jackie.

“Juliet sang the male part, which caused her distress,” the lawsuit said. “She considered this to be a huge step backward because everyone who listened to the song heard a boy, but Juliet knew she was a girl.”

The lawsuit contends the restroom rules violate Title IX, the federal law that bans sex discrimination in schools receiving federal funds, and the equal protection clause of the U.S. Constitution.

Although federal judges in North Carolina, Wisconsin and on the 4th U.S. Circuit Court of Appeals have agreed, others haven’t or simply haven’t had a case on which to rule.

So far, no judge in the federal Western District of Pennsylvania, where the lawsuit was filed, has ruled on the issue, nor has the 3rd U.S. Circuit Court of Appeals that oversees federal courts in Pennsylvania and several other states.

The lack of uniformity means the question will eventually be decided by the U.S. Supreme Court, said Bruce Antkowiak, a former federal prosecutor who now teaches law at St. Vincent College near Latrobe.

“It seems to be the next big issue that will be coming down the pipe,” Antkowiak said.