The year 1981 may go down in history as the date women's rights activists, like blacks before them, turned foursquare to the Supreme Court to obtain equality.

With the Equal Rights Amendment stalled and President Reagan in office, the women believed that the court's upcoming ruling in the all-male draft registration case could define their place in society for the next decade.

Exclusion of women from the military draft, like no other government policy, "consigns them to a second class status" says the National Organization for Women in a friend-of-the court brief filed with the Supreme Court. It gives a "governmental imprimatur" to sex discrimination, the organization told the justices, with "profound and harmful impact on women and society as a whole."

For women, said NOW President Eleanor Smeal, the case, Rostker vs. Goldberg, is the equivalent of Brown vs. Board of Education, which ended government-sanctioned "separate but equal" schools.

That view also is reflected in the friend-of-the-court brief filed last week by the Women's Equity Action League Educational and Legal Defense Fund on behalf of 11 women's organizations, including the League of Women Voters, the American Association of University Women and the Federation of Organizations for Professional Women.

The briefs constitute manifestos on discrimination against women in American society -- encyclicals of the women's movement that undoubtedly will survive the disposition of the case, for they will take the justices far beyond its legal issues.

Between the lines, the briefs also show a consciousness that the case could be the movement's last chance for a major victory for a long time. If the women win, Rostker vs. Goldberg might be equivalent of Brown vs. Board of Education, as Smeal put it. But if they lose, some fear, it could be their Plessy vs. Ferguson, the 1896 decision that enshrined "separate but equal" for blacks in the law for hald a century.

Exclusion of women from draft registration and from the draft is an act of stereotyping, the women have told the court. It is both the symbol of discrimination against women and a cause of much of it because it says, officially, that women are not the peers of men.

"It thus announces to women [and their male compatriots] that women constitute a different -- and inevitably lesser class from all men merely on the basis of gender," the NOW brief says.

And that stereotype -- the lesser class -- in turn justifies denial of all manner of benefits throughout society and perpetuats the status of women as "second-class citizens."

Psychologically, it feeds the feeling of defenselessness on the part of women that makes them more susceptible to "violence in their daily lives." And politically, it engenders the feeling that men, as NOW expresses it, are somehow more entitled to equal rights and high office because of their battle-worthiness.

Both briefs were prepared in consultation with lawyers for the men who first challenged the all-male draft in Philadelphia in 1971 and won, at the district court level in 1980, the case that is now before the court. The briefs are designed to represent the views the lawyers in the case cannot properly reflect because they represent men.

Both briefs are part of an ever-present subplot in Supreme Court cases, in which those not directly involved take on each other in a battle of friend-of-the-court briefs. NOW, for example, takes time in its submission to answer an earlier shot fired by a pro-all-male draft group organized by Phyllis Schlafly.

The Schlafly group argued in an unsuccessful effort to intervene in the case that the military is, in effect, a man's world where women don't belong.

"Women have responded with bravery and steadfastness when they have been required or permitted to fight for their country," NOW says. "These characteristics are individual ones, called forth when needed, and are present in varying degrees in members of both sexes."

Some of the fears of the Schlafly group "bear a striking resemblance to the apprehensions that preceded racial integration in the military . . . ," NOW contends.

Both the Womens Equity Action League and NOW punted on an issue that has caused major debate within womens' groups: what should happen to the draft registration program if it is ruled unconstitutional.

The justices have at least two choices. They can declare the entire program unconstitutional because it excludes women, and wipe it off the books. This would require new legislation, which might not pass. Or, the court could allow the program to continue so long as it includes women.

Many womens' rights activists are also antidraft, so they would like the law wiped off the books. Others believe that some draft registration program is necessary in the event of a military crisis.

The WEAL group said either remedy was feasible. NOW ignored the subject.

Neither ignored the potential consequences of losing the case, however, which they fear could be a major reversal for what has been a quiet revolution in the courts. Before the 1970s, legal distinctions between men and women could be enacted without fear of careful scrutiny by courts. Since then, the Supreme Court has required a substantial justification for gender distinctions and has overruled many of them as discriminatory.

Apart from its immediate affect on the draft registration, allowing this distinction to remain, the women fear, could cause judges to retreat to their pre-1970s tolerance.

"It could have a profound impact," Smeal said. "We'd really be going backwards."