Gov. Gavin Newsom sent a stern message Thursday to school leaders across California — any attempt to ban books from classrooms or libraries may require them to answer to the state attorney general.

In a letter to county and district superintendents and charter school administrators, Newsom, State Superintendent Tony Thurmond and Attorney General Rob Bonta cautioned against instituting any book bans.

Should a school still choose to remove certain instructional materials, the trio warns that it could be asked to explain its decision-making process to Bonta’s office.

“As state leaders elected to represent the values of all Californians, we offer our response in one shared voice: Access to books — including books that reflect the diverse experiences and perspectives of Californians, and especially, those that may challenge us to grapple with uncomfortable truths — is a profound freedom we all must protect and cultivate,” the letter read.

The free speech organization Pen America has found instances of book bans rising rapidly across the nation. During the first half of the 2022-23 school year, there were 1,477 cases of books being removed from schools, up from 1,149 in the previous six months, according to a recent PEN report.The American Library Association recorded 87 challenged book titles in 2022 in California, and almost all of the top 10 books targeted for removal revolved around LBGTQ issues. The two most challenged were “Gender Queer: A Memoir” by Maia Kobabe and “Beyond Magenta” by Susan Kuklin, according to the Library Association.

Book bans are frequently invoked by Newsom as a prime example of repressive policies in red states such as Texas and Florida, and a stark contrast to California.

The letter distributed to California schools on Thursday highlighted constitutional precedent and case law that officials say restrict the removal of books and mandate that school administrators preserve freedom of speech and academic freedom.

Newsom, Bonta and Thurmond said it was meant to assist school leaders with “fielding requests within your community while you continue to support your students and their educational rights.”