"Family Ties," now in its sixth year on NBC, is a broadly popular show, appealing in particular to youngsters and to women in the early thirties to mid-forties range. The mother and father -- nurtured in the 1960s by Bob Dylan, the Jefferson Airplane and the early Tom Hayden -- are unabashed liberals.

The most vivid and rebellious of their children is Alex (played by Michael J. Fox). Ideologically he is a fusion of Milton Friedman and the entire Federalist Society. Alex invariably gets the most acerbically witty lines -- a tribute to the liberals who produce and write the show and know that comedy, like lawyers, thrives on conflict.

While "Family Ties" has dealt with divorce and Alzheimer's disease, most of its episodes stay briskly clear of controversy. An exception was a two-parter in February. Titled "Read It and Weep," the script had to do with one of the frequent real-life attempts in the public schools to banish Huck Finn as a bad influence on children.

There have been a few documentaries (not on prime time) focusing on school book censorship and at least one after-school fictional special. But this was the first entertainment program to try to explore the politics -- personal and institutional -- of book banning. And it was done without dimming the comic thrust that its viewers expect of "Family Ties."

Jennifer, one of Alex's sisters, is told by her teacher that she cannot select "Huckleberry Finn" for her book review assignment because it has been banned from the reading list by the school board. Her parents are outraged. Her brother, Alex, being a libertarian conservative, is just as outraged, and quotes Justice William Brennan in the Island Trees case.

"Local school boards may not remove books from school library shelves simply because they dislike the ideas contained in those books, and seek by their removal to prescribe what shall be orthodox in politics, nationalism, religion or other matters of opinion."

This may be the first time a Supreme Court justice has been invoked in a sitcom.

The scriptwriters, Marc Lawrence and Alan Uger, defy television prime-time entertainment conventions by underlining -- without euphemism -- what offends many black parents about "Huckleberry Finn": Huck's best friend is often referred to by others in the book as Nigger Jim. But, says Jennifer, "the whole point of the story is how Huck learns that a man's color is not important, that everyone deserves to be free. Jim is the most noble character in the book."

While the school board objects to the use of the word "nigger" -- as if bigots of the time would have used anything else -- it also wants Huck thrown out on religious grounds. As the script points out, the dreadful boy says he'd rather go to hell than return Jim to slavery.

Jennifer will not yield, but neither will the principal and the superintendent of schools. Alex wants to make sure his sister knows the consequences of her stand: "You're going . . . to risk possible failure in English, jeopardize your chances of getting into college and become a social outcast in your own community."

"I guess so," says Jennifer.

"That's our girl," says her father, thereby putting an inspirational paternal glow on the First Amendment, which may be rather new to the millions of kids watching.

A particularly provocative subtheme of the program concerns Jennifer's English teacher, who thoroughly agrees with her position but, in fear of losing his job, flunks her on the book report and otherwise goes along with the authorities even when Jennifer is suspended.

In recent years, a good many teachers and school librarians have similarly betrayed their principles. Having assured their pupils that freedom of speech and press is the foundation of the nation, they have surrendered to the facts of economic survival. But some have not. A heroic exception was Irene Turin, a school librarian in the Island Trees, Long Island, School District. She publicly sided with the students who filed suit against the censoring school board and was punished in various humiliating ways for years after.

When I once asked her why she had put herself at such risk, Turin said, "It was very important for the kids to know that at least one adult was willing to stand up with them."

In "Family Ties," the teacher finally reclaims his self-respect, the family confronts the school board at a public meeting, and the school board is forced to call for a referendum on the issue.

Around the country, as school censorship battles continue to increase, "Family Ties" -- and its partner, Paramount Television -- could do one thing more. They could supply, at cost, videocassettes of "Read It and Weep" to be played at school board and parents' meetings -- and most important, in classrooms. I expect that Michael J. Fox may be a more compelling teacher of the First Amendment for kids than even Warren Burger.