In his first appearance as a member of the Loudoun County Library Board of Trustees last spring, Richard H. "Dick" Black intended to play the good soldier. He would sit quietly and listen to more experienced board members -- a role to which the retired Army colonel was not accustomed, having built a military career as a prosecuting lawyer and later as head of the Army's criminal law division.

On the board's agenda that day was a proposal from the libraries director that would allow library patrons to use the Internet without software designed to block pornographic material.

"I sat there and kind of waited for somebody I could follow to protest against it," Black recalled recently. "When they didn't, I said, I can't vote for this.' "

Black, the representative from Sugarland Run, went home and sounded the '90s version of a bugle call for the cavalry: He issued a press release, calling for site-blocking software on library computers.

Black enlisted other board members in his fight, and by October, the board had adopted, 5 to 4, one of the most restrictive Internet-use policies in the country, written by Black. Library patrons do not have access to sexually explicit material, e-mail or chat rooms, and children younger than 18 must have written permission from their parents or guardians to use the Internet.

This week, the issue reached federal court, when a group of citizens sued, charging that Loudoun County's Internet policy violates First Amendment rights.

"The key thing is that we're not necessarily opposed to filters, but if you have filters, adults should have the option of turning them off," said Jeri McGiverin, head of Mainstream Loudoun, a local civil liberties group involved in the lawsuit. The group's concern stems from the fact that the software blocks legally protected material, as well as pornography.

But Black, 53, is undaunted by the challenge. The man who flew combat missions in Vietnam sees Loudoun County's approach to the Internet as another battleground that must be taken -- for the good of women, children and the country.

"Most of the obscenity laws in this country are based on a community's standard of decency," Black said. "And the porn barons understand that once it's in the libraries, you can never prosecute an obscenity case because the defense will say, Hey, get off my back. It's in your own library.' There's a very genuine risk that it will collapse standards of decency around the nation."

Dick Black doesn't see his cause as a one-man crusade. He says most Loudoun citizens are behind him. But his opponents, though less successful than he, have been more vocal.

"I'm a conservative, but Black's so far right, he fell off the right," said board member George F. Hidy Jr. (Sterling), who voted against the Internet policy. "I have a hard time taking people's rights away. . . . I don't think we should be in the business of telling parents how to raise their kids."

County Supervisor James G. Burton (I-Mercer), who serves as a nonvoting member of the Library Board, said the policy violates First Amendment rights because the filtering software -- X-Stop -- blocks sites that are not pornographic, such as a Quakers site and one for the Heritage Foundation.

"I think some of {Black's} arguments are intellectually dishonest," Burton said. "For him to . . . argue that the software only blocks obscene material -- it turns out that's not true."

But Supervisor Steven D. Whitener (R-Sugarland Run), who appointed Black to the board, calls him a great leader. "This is not about censorship. This is about public money being used to pay for pornography."

Black, who studied law at the University of Florida, believes he hit on the proper approach to the problem when he titled his legislation: "Policy on Internet Sexual Harassment."

Without such a policy, Black said, Loudoun's library system is open to a lawsuit from women who feel intimidated in a public environment where men are free to call up pornographic images on a computer screen.

"Wherever you set up a sexually hostile environment . . . that denies women equal opportunities in the workplace," Black said.

"If you think about a library that has the Internet," he said, "a guy sits down and pulls up some really bizarre stuff, and a woman comes in at nighttime and wants to use the Internet.

"As she is trying to do some serious research, she's got this guy pulling up images of ladies and donkeys, and that woman is going to feel really tense. And she may feel physically threatened."

Trim and square-jawed, Black has the no-nonsense bearing of a military man, although he has been in private practice since 1995, a partner in his own Fairfax law firm.

Born in Northern Virginia in 1944, Black grew up mostly in Miami. The middle of three children and the only son, Black was a teenager when his mother was hospitalized for mental illness and his father took a job in New York, leaving the children in Miami.

He graduated from high school in 1962 and spent a year at the University of Miami. Then he ran short of money. Although the country was beginning to take on a rebellious air, Black was rooted in the 1950s idealism of family, church and country. He enlisted in the Marines and volunteered to serve in Vietnam.

"I felt like that was the duty of an American," he said.

Black said he flew 269 combat missions. Upon returning to the United States, he married a childhood friend and enrolled at the University of Florida, studying business and law and serving as one of only a few Republicans in a Democrat-dominated student government.

Returning to the military after college -- the Army this time -- Black spent 20 years combating crime on military posts. Black and his wife, Donna, have been married 29 years and have three children.

There are those who believe that Black is using the Internet issue as a springboard to political office. He has served as a campaign adviser to Mark L. Earley, a Republican state senator from Chesapeake who was elected state attorney general last month.

Black also has worked with the Christian Coalition, the League of Catholic Voters and the Law Enforcement Alliance of America.

Now he's contemplating running against state Sen. Charles L. Waddell (D-Loudoun). Waddell "represents old ideas that are out of step with the young people moving to Loudoun County," Black said.

Black believes that Loudoun residents want to set their own moral standards. Some counter that Black wants to do it for them. "Black's out for Black,," Hidy said.

One Library Board member speculated that Black, backed by conservative organizations, is using Loudoun as a testing ground for a national Internet-censorship debate. "When you change the social policy and release the anchor of any moral constraints and leave the nation in a moral drift, it becomes a very coarse and harsh society," Black said. "We have this evolving culture, where suddenly life is beginning to take on less meaning than it did. And it's all interlinked, see?"

The Internet policy "is not just a notion of nostalgia," he continued. "It's a notion that if we want to keep Loudoun County the kind of place where our children and grandchildren can grow up in a safe, happy environment, we have to take action now to preserve the culture. It depends on what we do right now." CAPTION: Richard H. "Dick" Black says libraries are an important battleground in the fight against Internet pornography.