The Supreme Court on Monday declined to hear a case claiming that the federal government’s male-only draft registration requirement discriminates against women.

The court shut down the challenge in an unsigned order. But Justice Sonia Sotomayor, joined by Justices Stephen Breyer and Brett Kavanaugh, added in a statement that they are watching Congress to see how it acts on recent suggestions that it extend draft requirements from just 18-year-old men to women as well.

“It remains to be seen, of course, whether Congress will end gender-based registration under the Military Selective Service Act,” Sotomayor wrote. “But at least for now, the Court’s longstanding deference to Congress on matters of national defense and military affairs cautions against granting review while Congress actively weighs the issue.”

Sotomayor’s statement aligned with the Biden administration’s position, which had urged the court to let Congress handle draft questions.

The challenge was brought forward by the American Civil Liberties Union, which claimed that the draft requirements, which have had no practical effect since the Vietnam War, sent a demeaning message to women.

“It’s also sending a tremendously harmful message that women are less fit than men to serve their country in this particular way and conversely that men are less fit than women to stay home as caregivers in the event of an armed conflict. We think those stereotypes demean both men and women,” said Ria Tabacco Mar, director of the ACLU’s Women’s Rights Project, as the court considered the case.

The court voted 6-3 in 1981 to uphold the male-only draft requirement. But much has changed since then, Sotomayor noted. In 2013, the Department of Defense opened combat roles to women. And two years later, it opened any position in the military to women.