Joan Dempsey Klein, president of the National Association of Women Judges, is descended from California's very first lawyer, John W. Kottinger. She comes from a family of lawyers and judges. But her parents didn't want her to go into law. And in all the schools she went to, counselors always said , "Why don't you be a teacher? That's what girls do. . . "

So she did. It wasn't until eight years after graduating from San Diego State that she took her law degree, in 1955. Within months she was named a deputy attorney general of California. And eight years after that Jerry Brown appointed her to the state supreme court.

She was in town this week for the convention of the association she helped found. Anyone who wonders why women judges felt they needed to organize should learn that of the nation's 15,000-plus judges, exactly 727 are women. Some have two or three. California, through the efforts of Gov. Brown, has 90 -- all but 10 appointed by him.

Washington does all right, too, Klein said. President Carter has named 40 women to the federal bench, and for this he is getting a special citation from the association.

Why an association of women's judges? The easiest answer is the sophomoric sex bias they face daily, the men who call them "honey" or "dear" instead of "judge," the partronizing and harassment that are only too familiar to all working women.

But there is also the Network. Many male judges who wouldn't dream of endorsing racially biased clubs still belong to men-only clubs. Men, particularly through the male-dominated American Bar Association, recommend each other for judgeships, look out for each other's interests, help along each other's sons and nephews.

"We have to build a network, too," said Klein, 56. "Of course we all belong to men's professional groups, and that's important. We need them. But we also need to develop our own power."

In one year, the association has doubled its membership to over 200. It will surely go on from there: With 45,000 women attorneys in the country and a law school population at least one-quarter female, the rarity of women judges is a sore point with them.

For instance, about 5 percent of appellate and general trial court judges are women, 7 percent of family court judges are women, 5.4 percent of all federal judges are women. There has never been a woman Supreme Court justice. Klein believes the best bet for President Carter's next appointment is Shirley M. Hufstedler, secretary of the Department of Education.

Klein is married to a lawyer. There are five children: her two sons, both headed for the law, and his three daughters. One daughter was accepted at a law school but went into radio instead.

"What we could use is a doctor and a dentist in the family," the judge muttered.

One reason she founded the organization was to do something about the lowered expectations most girls have to cope with, the suggestions from all sides that they try for nurse, not doctor, for teacher, not lawyer, and so on. A few years ago she headed a state committee to oversee the hiring of California's first highway patrolwoman.

"I'm very concerned with this fundamentalist movement we've seen during the election campaign, the people who preach that women's equality is somehow un-American and immoral and even sinful. We are good citizens. Many of us are wives and mothers. I just can't understand the kind of mind that doesn't want us to be treated equally. There's also the question of separation of church and state with all this religious politicking. We're trying to make the country a real democracy."

Her eyes flashed. "I'd like to talk to those people sometime. I really would."