WASHINGTON—Friday the Supreme Court announced that it is tackling liberals’ new sexual frontier, transgenderism.

At issue is whether any student or adult has a legal right to use bathrooms and showers alongside students of the opposite sex if that student or adult identifies with the opposite sex—an identity they can switch on a day-to-day basis.

The psychiatric profession classifies transgenderism as a disorder called gender dysphoria. The term covers men identifying as women or women as men, but also includes “gender fluid” persons who can identity as male on one day but a female on another day. It also includes “intersex”—people who refuse to ever be “confined” to identifying as male or female. There are other variations beyond these four.

High school student “G.G.” is a biological girl who calls herself a boy and dresses as a boy, with the support of her mother. They asked the teachers and the staff at student’s school in Gloucester County, Va., to call her by a boy’s name and allow her to use the boys’ facilities.

School officials tried to accommodate G.G., calling her by her preferred boy’s name. But they asked that she use the unisex bathroom in the nurse’s office rather than endorse her claimed right to use the boys’ bathrooms and locker rooms alongside biological boys and adult men.

But then G.G. changed her mind and decided she felt stigmatized by using a unisex bathroom, and demanded the school approve her use of the boys’ bathrooms and locker rooms at the same time as biological males are using those facilities. This demand goes to the heart of the transgender ideology, which says that government should require states, agencies, companies and individuals to accept the claims by transgender people that they be treated as members of the opposite sex.

The matter went to the school board, which adopted the policy that everyone must either use the facilities matching their biological sex, or instead use a single-person unisex bathroom.

G.G. sued, arguing that Title IX of federal law requires schools to allow anyone to use whichever facilities they identify with.

During the lawsuit, she got a low-ranking Obama administration official—James Ferg-Cadima, who was an acting deputy assistant secretary of education—to send her a private letter agreeing with her position.

The federal district court ruled in favor of the school administrators, but a three-judge panel of the U.S. court of Appeals for the Fourth Circuit—a panel with two liberals and one conservative—reversed in a 2-1 decision. The panel’s liberal majority held that the term “sex” in Title IX and Education Department regulations is ambiguous and has no clear meaning, and therefore that courts should defer to Ferg-Cadima’s private letter as an authoritative declaration of law.

Since then, President Obama’s Justice Department and Education Department have made an official statement that both Title IX and Title VII—which prohibits almost every employer in America from discriminating on the basis of sex—requires all schools and employers to embrace transgenderism, and that anyone who declines to do so can be prosecuted or sanctioned for violating federal law.

Almost half of the states in the nation are currently suing the Obama administration over this issue. In that case of Texas v. U.S., a federal judge ruled in favor of the states, which the Justice Department is now appealing to the Fifth Circuit appeals court.

Several other similar lawsuits are ongoing in North Carolina, where liberals are suing over a state law, HB 2, under which people use public restrooms corresponding to their original or changed sex marked on their original or updated birth certificate.

And in another case, Board of Education of the Highland Local School District v. U.S. Dep’t of Education, a liberal federal judge in Ohio recently went much further, ruling that school policies that do not embrace transgenderism violate the Fourteenth Amendment to the Constitution, a decision now being appealed to the Sixth Circuit appeals court.

But this case of Gloucester County School Board v. G.G. ex rel. Grimm can be decided on a much narrower basis. The justices could rule that private letters by low-ranking officials written to influence a lawsuit are not entitled to any deference by a federal court, and send the case back to the lower court for a new legal analysis.

This issue comes too late to be a major issue in the 2016 presidential election. But the transgender agenda is now going before the nation’s highest court, and the next president—Donald Trump or Hillary Clinton—will appoint the ninth justice who may be the tiebreaking vote on this issue, one that will spread to every school, restaurant, and workplace in America.

Gloucester County’s case will likely be heard around March 2017, with a decision by the end of June unless the Supreme Court still have only eight justices. It will likely deadlock 4-4 in the case.

Ken Klukowski is senior legal editor for Breitbart News. He is also senior counsel for First Liberty Institute and filed an amicus brief at the Supreme Court representing Catholic colleges in this case. Follow him on Twitter @kenklukowski.