The Biden administration has asked the Supreme Court not to take up a lawsuit that calls the all-male military draft unconstitutional.

Because Congress is considering whether women should also be required to sign up, acting solicitor general Elizabeth B. Prelogar said in a brief to the court, “any reconsideration of the constitutionality of the male-only registration requirement . . . would be premature at this time.”

The brief does not state whether President Biden thinks women should be included, nor does it defend the current system, which requires only men ages 18 to 26 to submit their information should a military draft be needed again.

“Congress’s attention to the question may soon eliminate any need for the court to grapple with that constitutional question,” Prelogar wrote.

The American Civil Liberties Union, representing two men and a group called the National Coalition for Men, challenged the men-only requirement as “one of the last sex-based classifications in federal law.”

“It imposes selective burdens on men, reinforces the notion that women are not full and equal citizens, and perpetuates stereotypes about men’s and women’s capabilities,” the ACLU’s brief told the court.

The Trump administration defended the current system in lower courts, and Biden’s Justice Department twice asked the court for extensions before filing its response.

Ria Tabacco Mar, director of the ACLU’s Women’s Rights Project, said the result was telling.

“Noticeably absent from the government’s brief is any argument that men-only registration is constitutional,” Mar said. “That is not surprising given that men-only registration is outdated, based on gender stereotypes, and no longer recommended by the military itself.”

A special commission set up by Congress to study the issue said last year that requiring women and men to register when they turn 18 would make it “possible to draw on the talent of a unified nation in a time of national emergency.”

Military leaders have said the same. But Congress has been reluctant. And the last time the Supreme Court considered the issue, it ruled that it was constitutional to require only men to register.

In 1981, the court ruled 6 to 3 in Rostker v. Goldberg that because the primary function of the draft was to form combat-ready forces, Congress was justified in treating men and women differently. At the time, women were excluded from combat roles.

But that is no longer the case. The military removed its categorical ban on women in combat in 2013. All jobs became open to women two years later.

A brief filed by retired generals supporting a registration change noted that women make up nearly 20 percent of the military now.

“Warfare today requires intelligence and communication specialists, linguists, logisticians, medical personnel, drone and cyber operators, and more,” their brief says. “Noncombat positions comprise nearly 80 percent of today’s military occupations.”

A district judge said that the changed conditions meant that the Supreme Court’s 1981 decision was no longer applicable. But a panel of the U.S. Court of Appeals for the 5th Circuit disagreed, saying only the Supreme Court could overrule such a precedent.

Prelogar said one thing that had not changed since 1981 was the court’s deference to Congress in making rules regarding military preparedness. She said lawmakers are now “actively” considering the recommendations of the National Commission on Military, National, and Public Service.

“Affording Congress a more realistic period in which to address the issue” would also be in keeping with the court’s reluctance to decide constitutional questions unless necessary, Prelogar wrote.

“Should Congress fail to act within a reasonable period to address the committee’s recommendations, this court would, of course, remain free to reconsider Rostker in an appropriate future case.”

Mar indicated that Congress was unlikely to act absent a ruling from the court.

“President Carter made the same ask in 1980, and Congress hasn’t fixed the problem despite having 40 years to do so,” she said. “It’s long past time for the Supreme Court to declare that men-only registration is unlawful sex discrimination.”

Even though there has not been a draft for decades, the registration requirement carries consequences. Men who do not comply could face criminal prosecution, denial of federal student loans, disqualification from citizenship and other penalties.

It could be weeks or even months before the Supreme Court decides whether to grant National Coalition for Men v. Select Service System.