Laura Murphy, a mother of four from Fairfax County, lobbied for legislation that would require teachers to inform parents about sexually explicit materials in coursework, and allow them to opt-out their children. Virginia would be the first in the country with such a law. (Jahi Chikwendiu/The Washington Post)

Lawmakers in Virginia moved forward Thursday with legislation that could make it the first state in the country to allow parents to block their children from reading books in school that contain sexually explicit material.

The bill would require K-12 teachers to identify classroom materials with “sexually explicit content” and notify parents, who would have the right to “opt out” their children and request that the teacher give them something less objectionable to study.

Opponents call it a slippery slope toward book banning; advocates say it is a parent’s right to control their children’s exposure, even if the books are considered classics.

It all started with Laura Murphy, a Fairfax County woman who said she was horrified to discover that one of her sons, a high school senior, had been assigned to read the 1988 Pulitzer Prize-winning novel “Beloved.”

The seminal work of fiction, by Nobel laureate Toni Morrison, is about a former slave after the Civil War, and it contains scenes of bestiality and gang rape and an infant’s gruesome murder.

Murphy said that makes the book inappropriate for young readers, and she ticked off other critically acclaimed works in the same category: “The Bluest Eye,” also by Morrison, “Invisible Man” by Ralph Ellison and “The Road” by Cormac McCarthy.

Schools in Virginia follow a similar procedure that allows parents to withdraw children from sex-education class. “It just stands to reason when walking across the hall to English class, to be consistent, the same policies should apply,” Murphy said.

About half of Virginia school districts already require teachers to give parents advanced warning of “potentially sensitive or controversial materials in the classroom,”according to a 2013 survey by the state Department of Education.

After a spirited debate in a Senate committee Thursday, lawmakers approved the bill 9 to 6, along party lines, except for Lynwood W. Lewis Jr. (D-Accomack), who voted yes with the Republicans.

Sen. Charles “Bill” Carrico (R-Grayson) said he had not read “Beloved” but based his opinion on excerpts, which he said could poison the minds of young people.

“Evil is just — when you plant the seed, it’s a kitten,” he said. “You feed it, it becomes a lion and it eats you.”

Sen. Janet D. Howell (D-Fairfax) said she reread the book over the weekend and praised Morrison for her place in the pantheon of American novelists.

“I think it’s a slippery slope that’s icy,” she said. “Great literature is great because it deals with difficult human conditions, not because it’s easy.”

Earlier this month, the House unanimously passed the legislation in a block of uncontested bills without debate — an indication that most lawmakers were unaware of the potential for controversy.

The bill has a good chance of Senate approval if Republicans, who have a one-vote advantage, stick together and Lewis continues to back it. It is scheduled for a Senate vote on Monday. House lawmakers would get a last chance to voice objections before the bill reaches the desk of Gov. Terry McAuliffe (D), whose spokesman declined to say whether the governor would veto it.

There is a long history of parental concerns about material taught in the classroom, and some individual schools and districts around the country have taken steps to remove “Beloved” and other novels from reading lists.

But this appears to be the first attempt by a state legislature to regulate curriculums in this way, said James LaRue, director of the Office for Intellectual Freedom at the American Library Association, which tracks such legislation.

The Virginia bill could become a model for the nation, LaRue said.

While his association believes parents have the right to decide what their children read, LaRue said he worried that educators would find the process so difficult that they would decide not to teach certain books anymore.

“The focus of this effort might be to discourage the use of this book altogether — and that’s the chilling effect,” he said

And he said the approach could also give the false impression that the most important thing about a particular work of literature is its sexual content. In that case, Shakespeare’s “Romeo and Juliet” becomes nothing but “teen sex and suicide,” he said.

Millie Davis, director of the Intellectual Freedom Center at the National Council of Teachers of English, said parents have gotten used to ratings on movies, based on instances of profanity and violence, but books should be considered for their educational value.

“Whatever happened on Page 32 of a book is not why the book was chosen,” she said.

Under the proposed legislation, it would be up to the state Board of Education to write guidelines — including the tricky task of defining “sexually explicit” — for local school districts.

In a letter to lawmakers, the National Coalition Against Censorship and like-minded groups said public schools can’t eliminate an idea simply because society finds it disagreeable. The groups also questioned how the government is supposed to determine whether material is “sexually explicit,” calling it an “over-inclusive and vague” standard.

“Under this standard, titles as varied, valuable, and time-honored as Anne Frank’s ‘The Diary of a Young Girl,’ Geoffrey Chaucer’s ‘The Canterbury Tales,’ and most works by William Shakespeare could be flagged,” the letter said.

Del. R. Steven Landes (R-Augusta), chairman of the House Education Committee, sponsored the legislation at the request of House Speaker William J. Howell (R-Stafford).

“My job is not to judge the literature, it’s just to provide the option to the parent,” he said.

Murphy’s initial effort to remove “Beloved” from Fairfax County classrooms in 2013 was unsuccessful. She took her cause to the state Board of Education, which began deliberating whether to amend state regulations. While she waited for her idea to clear procedural hurdles, Murphy said that she lobbied legislators for a new law.

In the meantime, the Fairfax County school system amended its rules and now notifies parents about sexually explicit books.

Asked about whether a state law would have a chilling effect on materials that teachers choose for their classrooms, Landes said: “That’s up to them.”