When the Soviet Union invaded Afghanistan in 1979, President Jimmy Carter took steps to prepare the nation for armed conflict. He reinstated the requirement, then lapsed, that young men register for the draft—and called on Congress to update the law to allow everyone to register, regardless of gender. Congress didn’t heed the call, and last week the Supreme Court announced that it would not take up the issue either.

Many see this as a missed opportunity. Men-only registration reflects the outdated and sexist notion that women are less fit to serve in the military and, on the flip side, that men are less fit to stay home as caregivers in the event of an armed conflict. Such stereotypes demean both men and women. Limiting registration to men also devalues the contributions of women who serve in today’s all-volunteer force. That’s why the ACLU filed a petition asking the Supreme Court to declare sex-based registration unconstitutional. (I am a member of the legal team.)

Rather than distance itself from these gender stereotypes, the Selective Service System doubled down in a recent public service announcement better suited for the cast of Saturday Night Live than the United States government. The 30-second ad shows a young man transform into a cartoonish G.I. Joe after registering for the draft; his mother, in shock, drops the dish she was washing.

“The United States Constitution prohibits the Federal Government from discriminating on the basis of sex absent an ‘exceedingly persuasive justification,’” wrote Justice Sonia Sotomayor in response to our petition. “The Military Selective Service Act requires men, and only men, however, to register for the draft upon turning 18.” But the court explained that it would not intervene while Congress considers a recent report recommending universal registration. “It remains to be seen,” the statement read, “whether Congress will end gender-based registration.”

The court doesn’t typically provide its reasons for declining to hear a case, so the short statement sent a powerful message that the justices should consider men-only registration significant. Equally noteworthy was the fact that Justice Brett Kavanaugh chose to join Justices Sotomayor and Stephen Breyer in signing it. The court hasn’t decided a constitutional case involving sex discrimination since the composition of the court shifted under President Trump, and some have wondered if the newest members would adhere to the heightened standard of review that has long applied in such cases. Monday’s statement reassuringly cited longstanding precedent, including several landmark cases litigated by the late Justice Ruth Bader Ginsburg during her years as director of the ACLU Women’s Rights Project. As those decisions recognized, gender-based distinctions in law are more often than not grounded in archaic stereotypes.

Critics from both the left and the right have argued that true equality requires abolishing registration, not extending it evenhandedly. That is precisely what the practical effect of our lawsuit, if successful, would have been. To be sure, a Supreme Court decision declaring registration unconstitutional on the grounds that it discriminates based on sex would not have blocked Congress from adopting a new registration scheme for men and women alike. But neither would it have mandated that Congress do so. Rather, one of the goals of the lawsuit was to prompt Congress to ask whether it is still necessary to register anyone at all. Our suit could also have opened up new possibilities, such as a program of national service, as retired Gen. Stanley McChrystal and others have recommended. Any of those results would be an improvement over our current, discriminatory system.

The Supreme Court last confronted gender-based registration in 1981, when it upheld the law because, at the time, women were also excluded from combat roles. But the core premise for the court’s 1981 decision is no longer true today: “The role of women in the military has changed dramatically since then,” the court noted on Monday. Most recently, in 2013, the military lifted the ban on women in combat in response to two lawsuits, including one brought by the ACLU.

Despite these changes, skepticism about women’s service has hardly lessened in over half a century. “We have been shocked to hear that women in Russia are going into the combat service,” intoned Senator Burton K. Wheeler on the Senate floor in 1945. “We are more civilized, more Christianlike, than some nations that have done such things.” In 1980, the Senate committee that considered—and rejected—President Carter’s request to expand registration concluded that “drafting women would place unprecedented strains on family life.” The report described the possibility that “a young mother” could be called to service while “a young father remains home with the family” as “unwise and unacceptable to a large majority of our people.” And significant opposition remains today. The current ranking Republican member of the Senate Armed Services Committee warned that there would be opposition to the “controversial” idea that women could be called to serve alongside their brothers.

Though Congress has proved stubbornly resistant to change, a prod from justices across the ideological spectrum provides reason to hope that this time will be different. And, if not, we’ll be knocking at the Supreme Court’s door once again.