They are the kids in the middle, the ones who would have to trek to the post office to fill out a card that could someday send them to war. So they are fighting it -- or rather, it is being fought for them.

They are the class in the American Civil Liberties Union's class action suit to derail registration: 16 young men from 11 states. There are no women in the group because the ACLU has pegged its first antiregistration salvo on sex discrimination grounds, contending the scheme is unconstitutional because it involves only men.

But the ACLU 16 are far from a cross-section of even their male peers. They are too educated, too liberal, too upper- and middle-class -- a 1980 version of the kind of youths who so often managed to duck the draft a decade ago, while poorer, less advantaged teen-agers went off to the jungles of Vietnam.

Interviews with nine of the plaintiffs and the parents of three others found 10 of them college-bound in the fall, to such places as Columbia, Vassar, Oberlin, Antioch, Colby, the Eastman School of Music. One will be a high school senior; the other is working.

Their parents head a nationally known research center, a regional Chamber of Commerce, a Jewish war veterans auxiliary, an advertising firm, the ACLU itself. There are four college-level teachers, a doctor, a retired hospital president, a loan analyst, a social worker, a music librarian, a bank teller, a postal worker.

But regardless of the demographics of their group, the ACLU 16 believe they are fighting for everyone's neck, battling not registration but the draft. t

"Only naive people believe that there's a distinction, or that one won't lead to the other," said Dale Ewart, who lives in a suburb of Detroit.

"Registration itself isn't such a bad infringement on our privacy," said Peter Wogan, a native of Riverton, N.J. "My name is probably in hundreds of computers as it is. My privacy has alreay been infringed."

Most do not enjoy the notion that military force is sometimes necessary; many have fathers who fought in World War II or Korea. "This day and age has made it necessary," said James Barnett, who lives in Jackson, Miss. "People make it necessary."

But they view the registration plan as politically motivated militarism, intended to protect business, not the nation.

"You're not defending yourself," says Wogan, a practicing Quaker. "You're defending the huge American machine which is guzzling up oil, defending the corporate interests. I'd be willing to sacrifice some of the things we'd be fighting for."

Wary of the stiff penalities they would face -- fines of up to $10,000, imprisonment for up to five year -- most of the ACLU 16 plan to register by the deadline of their suit hasn't blocked the requirement to do so.

"I do fear reprisals," said David Halperin of Bethesda, whose father, Morton H. Halperin, heads the Center for National Security Studies. "At this point, I don't want to break the law. It's still not a draft. It's still completely giving myself up."

"I'm not sure that it wouldn't be some sort of romantic martyrdom," said Kenneth Blum, a physics major at Oberlin who wants to become "a socially conscious scientist."

"I don't want to make an empty gesture."

But Ewart plans to defy the registration order, despite ACLU warnings that his participation in the suit could make him an early target for prosecution.

"I'm willing to run that chance," he said. "Feeling the way I do, I can't lend myself to the system I condemn. By taking that action I'm proving it."

Like several of the plaintiffs interviewed, Ewart is uncomfortable with the sex discrimination grounds of the ACLU suit, filed last week in U.S. District Court here.

"No one should be drafted, not men, not women," he said. "Having women in the selective service . . . just increases the injustice."

Wogan agreed. "I don't like it to seem like I'm in favor of having women drafted. It's a shame we have to go about it that way."

But Jay Goldring, a student at Columbia, says his "main interest in the suit is that women should register; it's not to kill the draft altogether. Women should share the burden."

The young men arrived as principals in the ACLU's suit by different paths. Several led campus antiregistration groups and were contacted by local ACLU officials they knew. Some called to volunteer when plans for the suit filtered down to them through friends. One responded to a notice posted at his high school.

David Glasser heard about it from his father -- the executive director of the ACLU.

Ira Glasser said his son "was asking me some nervous questions about it six months ago, when talk of a draft was in the headlines. It's the kind of anxiety you see in people who are facing jail or indictment."

"I didn't really think of him as a plaintiff in a law suit. He's not an activist; he doesn't go to demonstrations." To avoid pressuring his son, Glasser had another ACLU official contact him.

"They have varying degrees of political awareness and political involvement" Ira Glasser said of the plaintiffs. "They're all very anxious about what [registration] will mean to their lives. It's not an abstract issue to them."

But those who thought to muster opposition to registration found it was an abstract issue to many of their peers.

Frustrated, they have come away from the effort endorsing the popular theory that theirs is a self-centered generation.

"This isn't 1968, unfortunately," said William Wolfe, just graduated from a San Francisco high school."There are a few who are very upset and a lot of kids who are just worried about grades."

Said Ewart, "Too many people, especially my peers in college, take their ideals, put them in their back pocket, and go off and make themselves money."

The young men are spurred, nonetheless, by the belief that they are doing something important for the rest of draft-age America -- whether it appreciates it or not -- for the country as a whole, and for themselves.

"It will make me more of a complete person, and less of a clone," said Kerwin Wyche, entering his senior year at a Richmond high school. "It takes a lot of courage, I think, to stand up for what you believe in, especically [concerning] something as controversial as the draft."

Involvement in the suit already has had a modest impact on some of the plaintiffs.

Goldring got "frantic calls" from relatives after his picture appeared in a paper in Chicago, his hometown. "My grandmother told me to be a martyr. All my relatives are worried that I'm going to be blacklisted by the government and never get a job."

Wolfe found he had become a minor local media celebrity. "I did not know that I would be such a figure, or such a figurehead I should say -- a symbol for something to show people that 18-year-olds exist."

And while some of the 16 has encountered the harrassment a few had expected, Wogan found his involvement in the suit encouraged some people to view him as an unpatriotic extremist.

"People have called me a radical," he said, but he added, "I'm definitely not up for communism, blowing up the Capitol. I really do despise communism."