They're stately and plush, venerable and elite, institutions where the wealthy and powerful traditionally come to relax and chat. And, says Lee Ellis, president of the University Club of Washington, "They're under attack."

Ellis' speaks comfortably, for his organization sits as a casual spectator in the fast-emerging battle between private clubs and local governments. Three years ago, the 83-year-old University Club voted to open its membership to women, and Ellis stresses that he is glad it's "on the right side of the wave."

Around the country, and most recently in Washington, private clubs that still maintain one-sex-only membership policies are being confronted by city councils hammering antidiscrimination legislation on the clubs' front doors.

Such legislation states that the clubs, under a variety of criteria, fit the definition of a "public accommodation." They therefore cannot selectively exclude the public, specifically professional women who argue that being barred from joining private city clubs, reputed to be informal centers of business deals and contacts, denies them equal opportunity.

"This controversy has become much, much more intense in the past few years, and especially in the past six months or so," said Aubrey King, a vice president and director of government relations for the National Club Association. The association represents nearly 1,000 private clubs in the United States, and about 10,000 local residents who belong to some of the District's 12 city clubs.

"We're facing an inquisition, and it's spreading rapidly around the country," said King.

On Sept. 29, the D.C. Council voted unanimously to extend its antidiscrimination law to cover the District's major private clubs. Patterned after a 1984 New York City statute, the measure states that an all-male club must admit women -- and vice-versa -- if it has at least 350 members, serves meals regularly, and receives outside payment for dues or rental facilities. Political and religious clubs are exempt.

While protests have focused on the all-male Cosmos and Metropolitan clubs, other city clubs, such as the all-female Sulgrave Club, and the Prince Masons, an all-black fraternal order, also will be affected by the council's actions.

King contends that the measure is built upon a false premise: that membership is so vital to career advancement it justifies "sweeping government activity." Ellis said he worries the measure will require private clubs to allow "anyone off the street" to sleep or eat at a private club.

Still, similiar legislation has passed easily in Buffalo, Chicago, Detroit and Los Angeles this year. It is being considered in San Francisco. In 1986, the Philadelphia City Council dropped a measure to bring private clubs under its antidiscrimination law when the council's primary target, the city's Union League Club, voted to accept women.

Last Monday, the U.S. Supreme Court announced it would examine the New York law, which has been challenged in New York for three years and most recently upheld by the state's highest court. Earlier this year, the court ruled Rotary Clubs must open their membership to women. In 1984, it ruled the Jaycees had to open its membership to women.

If the Supreme Court overturns the law, it will likely invalidate the District's measure, as well as legislation passed in other cities, King said. He said if the court upholds the law, it will lead to the demise of private clubs.

"This law has been bitterly challenged. It's been quite extraordinary," said Carol Ziegler, general counsel for the New York City Commission on Human Rights, which is responsible for making private clubs comply with the law. "It's amazing the amount of money and time some of these clubs have been willing to commit to battle this."

After voting down the idea in January, the University Club of New York, one of three primary targets at which the city's law was aimed, voted to accept women last spring, Ziegler said.

"When they realized what they had done in January, and how much voting to go private would cost them, they said to hell with that, and decided to vote again," said Harold Tyler, a New York lawyer who quit the club in protest of its January vote. "The whole thing is ridiculous."

Last week, the city's 139-year-old Century Club voted to accept women if the Supreme Court upholds lower court decisions. The Union League Club of New York is still arguing its case before an administrative judge, Ziegler said.

Proponents of the antidiscrimination legislation cite a constitutional guarantee of equal opportunity. The clubs' legal fight has focused on the constitutional guarantee to freedom of association, which they say is violated by the antidiscriminaton legislation.

"I firmly believe that each and every person has a right to socialize with whom they choose," said Phillip Israel, president of the 124-year-old Metropolitan Club of Washington.

Like other club presidents, Israel declined to discuss the issue, but said the club will now take a "wait-and-see" attitude toward the D.C. Council's bill, which is still subject to mayoral veto (Mayor Marion Barry has said he will sign the measure and congressional review.

Under the D.C. measure, and the New York law, private clubs have one of two choices: open their membership to both sexes, or choose to declare themselves distinctly private. Ziegler said clubs are extremely hesitant to "go private" because members would be forced to pay their own dues, and the clubs would have to end all contact with the public, including lucrative room rentals for banquets and parties.

"Since these clubs depend significantly on the economics of their restaurant business to survive," said District council member Jim Nathanson (D-Ward 3), who sponsored the antidiscrimination measure, "that restaurant business is not distinctly private; the public is let in at the selection of club members."

If the District measure becomes law, Nathanson said, it can be enforced only if someone files a discrimination complaint against a club. One possible response to such a complaint, if proved true, could be revoking the club's liquor license.

Nathanson said that the "significant divisions" within clubs about the issue will lead to this scenario: a club member favoring membership for both sexes will sponsor a member of the opposite sex to join the club. And if he or she cannot be admitted because of sex, then a complaint can be filed.

"These clubs have a choice: enter the modern world, or revamp their restaurant business and not allow nonmembers in," Nathanson said.

Since the University Club of Washington opened its membership, club president Ellis said only about a dozen women have joined, some of whom now serve on club committees. The first -- 36-year-old Alexandria architect Jo Anne Murray -- declined to discuss the arguments in the present debate, but said membership allows her "valuable association with respected members of the business community."

Aside from a women's locker room, Ellis said opening University Club membership -- "it was contested, but wasn't a bloody feud," he says -- has prompted few changes in the organization. As is the case at other private clubs around the country that have recently knocked down sex barriers, very few women have expressed interest in joining, Ellis said. He said he's not sure why.

Nathanson said the number of women joining private clubs will increase very slowly because the thought -- much less the possibility -- of doing so is brand new. "As women become more successful, these clubs will feel more pressure," he said.

Nearly 38 percent of all the executives, administrators and managers in the United States are women, according to Bureau of Labor Statistics. In 1977, women held less than 25 percent of those positions.

That increase is partly responsible for what Ann Lewis, head of the private clubs discrimination project of the Americans for Democratic Action, calls the "sudden, growing consciousness" about private clubs' sex discrimination. Three years ago, she said, it was difficult to convince women the issue was important.