Among the big stories that emerged at the tail end of 2015 but got limited-to-very-limited attention was the Pentagon’s decision to clear women to serve in all combat roles.

The Fix put the decision on our list of big stories in gender news for 2015. We even advised readers to stay tuned for the debate that was likely to follow about whether this change also required Selective Service reforms. If women are now eligible to serve in all combat roles, should they also be required to join men on the government's mandatory registry of Americans who can be drafted into military service?

And yet, on Saturday, whatever portion of America that was watching the Republican presidential primary debate witnessed that issue get its first mention on during a Democratic or Republican presidential primary debate.

What viewers got were clear answers from former Florida governor Jeb Bush, New Jersey Gov. Chris Christie and Sen. Marco Rubio (R-Fla.) supporting the idea of including women in the registry mechanism, which would be put to full use in the event of a draft.

Retired neurosurgeon Ben Carson asked for time to answer the question and then did not do so, exactly. He commandeered time to run though his views on the need for more comprehensive mental health and social services for veterans to be paid for from a type of individual medical savings account Carson has tried to advance throughout the campaign. Carson ended his comments by declaring that such changes would help to improve the lives of veterans — that volunteers would make a draft permanently unnecessary.

Carson’s response was, in odd way, both a strong and weak moment for the candidate and his flagging campaign. Carson has struggled to command time and attention, and even manage many of the questions directed at him specifically during previous debates. On this count, he essentially strung together several of his ideas into an answer which seemed to begin just slightly off the question's target. But the factual premise of Carson’s idea is a bit shaky.

The United States last instituted a draft in the run-up to the Vietnam War. The concept of an all-volunteer army was discussed, debated and became a campaign issue in the decades that followed. In the late-1960s, Richard Nixon campaigned on a platform that included ending the draft. In 1980, the Carter administration re-instituted the requirement for all men (native-born and immigrant non-citizens) to register with the Selective Service within 30 days of their 18th birthdays.

However, the draft has not been implemented or used in any conflict in the intervening decades, and an “all-volunteer” Army currently provides the human element of the nation’s defense infrastructure. In essence, the United States has had an all-volunteer army for more than 40 years. That’s the situation, despite whatever flaws exist and persist in veterans’ health care and social services.

In fairness to Carson, Christie was the only candidate who spoke Saturday about the possibility of women registering with Selective Service (as men are already required to do) in terms that do not fall in the well-trodden GOP path of advocacy for a robust and large military. Instead, Christie seemed to speak to the social and civil-rights questions inherent to the issue.

Christie, who rarely passes on an opportunity to remind debate viewers that he is a lawyer and former federal prosecutor (or, as he prefers to put it, “law enforcement” official), had what most debate moderators considered a strong evening overall.

But on the question of the draft, Christie described the need to include women in any registry as a matter of fairness, equal access and opportunity for women. And he described such a change as consistent with American law and with what he strives to teach his daughters about their abilities and obligations.

It was an answer that, for Christie fans and those newly intrigued by him Saturday night, seemed to say very clearly that he is a modern Republican man. However, for Christie’s critics, it was an answer that stood in sharp contrast to his insistence that government policy should control women’s reproductive options. More than a few voiced those views on social media.

For their parts, Rubio and Bush quickly pivoted to their ideas on the need for a larger military. Bush also occupied some awkward seconds in which he repeatedly insisted that he was not calling for the country to re-institute the draft despite the fact that this also was not the question the moderator asked. In doing so, he also highlighted one of the reasons that most politicians dread any discussion of the draft at all.

War is often unpopular. And rules compelling people to send their sons and daughters to fight a war are always controversial.

Still, it was a moment worth noting and one that seems very likely to resurface — or at least should — as the 2016 campaign moves forward.