It was in 1981 that the United States Supreme Court, in a decision that I still have trouble explaining to my students when I teach it, held that it was constitutional for the Selective Service, acting under the authority of Congress and the president, to require all men — but not women — between the ages of 18 and 25 to register for a potential draft.

Why, at a time when the legal distinctions between men and women for purposes of employment, family law and government benefits were all falling based on the constitutional guarantee of equal protection, was it still permissible to discriminate in the registration requirement?

Probably for the same reason that even my liberal friends looked at me like I was out of my mind when, a year before, as a staffer on the Senate Judiciary Committee, I suggested that we needed to examine the constitutionality of excluding women from combat. "Are you nuts?" people asked.

There have always been good reasons to question the exclusion that limited the role of women in the military, reasons that were raised by a lawsuit brought two months ago by four servicewomen and that were finally addressed when Defense Secretary Leon Panetta announced on Thursday that the ban will be lifted.

For one thing, "combat" doesn't necessarily mean what it once did when wars were fought primarily by men in trenches on the front lines. Is driving a truck down a road that may be mined with explosive devices "combat"? Technically, no, although it is surely dangerous. Modern wars are fought by women who risk their lives every day even if their positions are classified as "non-combat." In the past year, the military reclassified 14,500 positions to open them to women and jettisoned the rule that had prohibited women from living with male combat units.

Equally important, if women are excluded from "combat positions" and particularly from combat leadership positions, they will be — and have been — stymied in their efforts to be promoted to the top ranks of the military. Combat experience — and especially leadership of combat units — is a key factor in promotion decisions, which is one important reason why so few women have made it to the top.

In many respects, the military is the most equal institution in our society. Minorities have achieved greater success in the military than in almost any private sector company. Women have received training in "nontraditional" occupations, which many take advantage of when they leave the service.

So why the continued ban on women in combat? Why the vestige of single-sex registration?

The short answer is that war has always been different. The last vestige of sexual stereotyping is grounded in the role of men as warriors, and in the fear or stigma, call it what you will, that women who are captured as prisoners of war would not only be killed, as men are, but also sexually assaulted.

In a joint press conference with Panetta, Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, suggested that the ban on women in combat positions actually contributed to the increasing incidence of violent sexual crimes within the military. "We've had this ongoing issue with sexual harassment, sexual assault. I believe it's because we've had separate classes of military personnel at some level. Now, it's far more complicated than that. But when you have one part of the population that is designated as warriors and another part that is designated as something else, that disparity begins to establish a psychology that, in some cases, led to that environment. I have to believe that the more we treat people equally the more likely they are to treat each other equally."

Amen.