A federal judge’s ruling that it is unconstitutional to require men, but not women, to register for a draft into the U.S. military has revived a debate about whether the system should be altered or ended. 

But the decision, which does not order the government to revise the registration requirement, also raises a question: What happens next?

The Selective Service System, created at the outset of World War I, requires men ages 18 to 25 to register and was last used to send draftees to combat during the Vietnam War. But whether it is constitutional has been debated for years, especially after the Obama administration in 2015 rescinded a policy that prevented women from serving in most ground-combat roles.

U.S. District Judge Gray H. Miller said in his ruling Friday that times have changed and the government can no longer justify the male-only system’s “gender-based discrimination.”

“While historical restrictions on women in the military may have justified past discrimination, men and women are now ‘similarly situated for purposes of a draft or registration for a draft,’ ” Miller, a judge in Houston, wrote in his 19-page opinion .

“If there ever was a time to discuss ‘the place of women in the Armed Services,’ that time has passed.”

The decision is unlikely to be the last word in the long-running debate. The case was brought by the National Coalition for Men, a nonprofit men’s rights organization, and two draft-aged men, one in Texas and the other in California. 

“This ruling is going to force the government eventually to either get rid of the selective service requirement or require both sexes to register. It’s got to be one or the other,” said the coalition’s attorney, Marc Angelucci.

A similar case, pending in federal court in New Jersey, was brought by a young woman seeking to register for the draft. She has also challenged the constitutionality of the male-only requirement.

The cases come as the National Commission on Military, National, and Public Service, formed in 2017, interviews Americans about how they view the Selective Service System and prepares recommendations due to Congress next year about what to do with the draft and how to make national service more desirable. 

Joe Heck, the commission’s chairman, said Monday in an interview that the group has been monitoring both court cases and the decision Friday makes its work more relevant. Research has shown that a small majority of Americans believe that women should register for the draft, and the information the commission has gathered anecdotally backs that, he said.

But Heck, a one-star general in the Army Reserve and a former Republican congressman from Nevada, said that many Americans are entrenched in their positions, often falling along generational lines.

“It does seem like the folks for and against fall into two distinct groups,” he said. “The younger folks — the 18- to 25-year-olds — are all saying that, yes, women should have to register. That it’s a matter of equality — and that’s both males and females. But when you get to an older demographic, those are the ones who are more reluctant to have women register. Those are the ones saying, ‘Don’t draft our daughters.’ ”

A Pentagon spokeswoman, Air Force Lt. Col. Carla Gleason, referred questions about the ruling to the Justice Department.

“We need and appreciate every qualified patriot who is willing and able to serve,” she said.

The Justice Department declined to comment or to say whether the government would appeal. 

Because the decision does not include an injunction blocking the government from continuing with the requirement, the question remains: “How do you fix this?” said Eugene R. Fidell, who teaches military law at Yale Law School. 

“By getting rid of draft registration for everybody or imposing draft registration for women? The judge hasn’t ruled on that,” he said. “Either of those outcomes would satisfy an equal protection claim.”

Government lawyers had urged the judge to defer to Congress on military affairs and to put off a decision while the national commission considers whether lawmakers should revise draft registration requirements. 

But Miller, who was appointed to the bench by President George W. Bush, noted in his ruling that the commission is not due to issue a final report until 2020 and that Congress has debated the requirement “for decades with no definite end in sight.”

Miller acknowledged that his ruling is at odds with a 1981 Supreme Court decision that upheld the constitutionality of a male-only registration requirement. But the high court’s holding in Rostker v. Goldberg is not directly on point, the judge found, because women are now eligible to serve in combat roles.

In December, Ash Carter, the former Pentagon chief who opened combat jobs to women, said in a report for the Harvard Kennedy School that the question about whether women should register for the draft “arose immediately” after the combat-exclusion policy was rescinded.

“At the time, I said that it stands to reason that if women are admitted to all positions in the military, they should be subject to the draft,” he wrote. “However, the law remains that women are not currently required to register. In fact, it does not matter much to me, since I do not want a draft. I want to be able to pick who joins us.”

The top officers in the Army and Marine Corps, Gens. Mark A. Milley and Robert B. Neller, also have said they are in favor of women registering for the draft.

A number of advocates for women serving in the military, including the Service Women’s Action Network, have argued for female registration as an equal rights issue.

Others have argued that the United States is due to ditch the Selective Service System entirely.

Christopher Preble, a Navy veteran and defense analyst with the libertarian Cato Institute, said Monday that he is glad the debate over whether women should register for the draft has prompted the United States to revisit the need for the system.

“We know from bitter experience that the manner in which people are chosen from that pool is not equitable,” he said, referring to the ways in which some people avoided military service, including through deferments. “It wasn’t in Vietnam, and it wouldn’t be in the present era. And so I just don’t see the rationale for registration, which implies that every male at that age is expected to be called in service in the event of a national emergency.”

The coalition and the men behind the court challenge in Texas — Anthony Davis and James Lesmeister — argued that the male-only requirement violated the equal protection clause of the Fifth Amendment. 

“We take no position on whether there should be a draft,” said Angelucci, their attorney. “We just feel if there is a mandatory requirement, it should not be discriminatory based on sex.”

Correction: Joe Heck is a former congressman from Nevada, not New Mexico. The story has been updated.