A federal appeals court on Wednesday blocked a Texas law that would require ratings from booksellers that deal with school libraries, agreeing with a lower court that found it unconstitutional.

The 5th U.S. Circuit Court of Appeals, based in New Orleans, said in a decision published Wednesday that the state could not violate the Constitution.

“We agree with the State that it has an interest in protecting children from harmful library materials. But ‘neither [the State] nor the public has any interest in enforcing a regulation that violates federal law,’” the appeals court wrote.

The decision bars the Texas Education Agency from enforcing the law.

Those who sued to block the Texas law, which include bookstores and associations representing authors and publishers, said that the appeals court decision was historic and that it protects authors and lets parents make decisions about their children without government interference.

“This is a good day for bookstores, readers, and free expression,” the plaintiffs said in a joint statement.

The law, passed last year by the Republican-controlled Legislature, would have forced any bookseller to public schools to rate books for sexual content.

The law prompted warnings that its broad language could lead “Romeo and Juliet,” “Of Mice and Men,” “Maus” and “I Know Why the Caged Bird Sings” to be banned or restricted, according to a lawsuit booksellers filed last year.

It was set to go into effect on Sept. 1, with ratings due on April 1, according to court documents. The lower court issued an order blocking enforcement of it in September.

The lower court found that decisions in other cases compel “a conclusion that the statute is unconstitutional” and that the Supreme Court has ruled that people are free from speech that is compelled by the government.

In that lower decision, U.S. District Judge Alan Albright found that sections of the law — the Restricting Explicit and Adult-Designated Educational Resources Act, or READER Act — are unconstitutionally vague, noting a large variance in grades and ages for which booksellers would have to try to account.

The Texas Education Agency did not immediately respond to a request for comment Wednesday night.

The appeals court found that the bookstores and others suing against the law were likely to succeed on the merits that the act violated their First Amendment rights.

It also found they stood to suffer irreparable economic injuries. One of the booksellers, Blue Willow, argued that it had sold $200,000 worth of books to a school district in Katy over the last five to seven years but that the district has now paused all purchases from any seller.

The law also means booksellers would have to rate books already sold. Blue Willow estimated it would cost $200 to $1,000 per book to comply with the law and $4 million and $500 million to rate books already sold — when its annual sales are just over $1 million, according to the appellate court opinion.

Laura Prather, an attorney who represents the plaintiffs, including book seller BookPeople, said that the appeals court decision was “a win for Texas and a win for free speech.”

“The book rating system in HB900 is a clearly unconstitutional requirement that would irreparably harm booksellers across the state,” she said in email, referring to the House bill number. “We’re thankful the Fifth Circuit recognized it would require booksellers to speak against their will and the importance of blocking it from taking effect.”