THE SUPREME COURT, as retiring Justice Potter Stewart said, is not a representative democracy nor, with its history of male justices, has it ever been. And with that said, he argued against appointing a woman to the highest court of the land solely because of her sex. "It's an insult to the court, to the appointee and to the American public to appoint somebody just because he or she is not a white male," said Stewart following his retirement announcement.

Having served on the court for 23 years, Justice Stewart is understandably protective of it; he does not want to see it diminished by a selection process that yields quality of justice to sexual favoritism. And so, in what was surely an unitentional insult, he suggested that President Reagan choose either quality or a woman or a minority. The two, however, are not mutually exclusive.

The names of a number of women judges have surfaced in the wake of Stewart's announcement and none has met with criticism that she is incompetent. At the same time, a number of men's names have surfaced and none of them has been heralded as being of such eminent legal stature that he dwarfs the competition. In the absence of the second coming of Felix Frankfurter, then, the reasonable expectation is that a White House search for a legal giant to fill Stewart's seat will produce, at worst, a midget plucked from Reagan's political set, and at best, a regulation-size human being who is well connected politically, of conservative stripe and of good reputation in his profession.

Justice Stewart's argument is that a person should not be chosen strictly on the basis of sex, and he is certainly correct. But to say the court is not a representative democracy is a neat way of overlooking the historical facts of how justices have been selected. They were, or course, not just chosen because they were men. Nor were they selected merely because they were the greatest legal minds of their time, nor because they just happened to be of the same political affiliation as the president. No, there were other factors. It has long been seen as desirable, for example, for the court to be geographically representative of the entire country. That way no part of the country can be made to feel that it is being subjected to the will of hostile geographical interests dominating the court of last resort. In modern times, it has become desirable to have someone who was representative of the Jewish population on the court, and then, of the black population. As presidents have considered appointments, they have also sought to balance the court in terms of age.

Three years ago, the Federation of Women Lawyers formed a judicial screening panel whose purpose was to screen all judicial candidates for their demonstrated commitment to equal justice for those who have traditionally gone unrepresented. President Carter, in making 152 appointments to the federal bench, took that as yet another standard to be met in judicial appointment.

It is that concept of equal justice that is the most powerful arguement for appointing a woman to the Supreme Court now. As it stands, the court is the supreme institution of authority and it is the only one that had not been sexually desegregated. How, given the male- only history of the court, as well as the legal profession, can a woman believe she is getting equal justice?

The interests of women are before the court as never before. The flood of sex discrimination cases that began in the '70s will continue during the next decade whether the Equal Rights Amendment is ratified or not. The court recently opened the door to a whole series of cases involving the concept of equal pay for work of comparable value, a concept its proponents believe will go far to correcting the low wages associated with jobs traditionally performed by women. Cases involving divorce, statutory rape, parental rights of lesbian mothers and abortion will continue to come before the court for resolution. Both the court and the American public will be best served by having the voice of at least one woman sharing a female perspective brought to bear on these issues with eight men. A woman on the court might not have kept it from upholding a patently discriminatory law as it did last week in the draft case, but the American public would have known that a woman's opinion was at least expressed in the deliberations.

That such a voice is needed in the interests of equal justice, and that it is needed sooner, rather than later, was compellingly demonstrated by the court itself on June 1. That day the court ruled that a woman fighting to retain parental rights to her child did not have a constitutional right to a lawyer. That same day, the court ruled that a father fighting a paternity suit had a constitutional right to a state-financed blood test. A court that finds access to a blood test to fight paternity more constitutionally compelling than access to a lawyer to fight permanent loss of a child, could surely benefit from what we used to call a woman's touch.