Iowa’s Mason City Community School District is pulling 19 books from school libraries that administrators found to contain “a description or depiction of a sex act” in order to comply with Republican-backed state laws. A key arbiter of whether the books should be banned: ChatGPT.

The news that the district had used AI software in its decisions was first reported by the Mason City Globe Gazette last week, but it wasn’t clear what tool was used — or how exactly officials went about doing it — until Popular Science reported that ChatGPT was used. The banned books include The Kite Runner by Khaled Hosseini, The Handmaid’s Tale by Margaret Atwood, and I Know Why the Caged Bird Sings by Maya Angelou.

According to Popular Science’s reporting, administrators inputted the query, “Does [book] contain a description or depiction of a sex act?” into ChatGPT for each book that is commonly challenged.

“If the answer was yes, the book will be removed from circulation and stored,” Bridgette Exman, assistant superintendent of curriculum and instruction of Mason City, told Popular Science.

Exman told the outlet that it was impossible for the district to read each potential book on the list to look for instances that could violate a sweeping state law enacted in May. Even with the new school year around the corner, many educators and districts say the state hasn’t provided clear guidelines on how to implement changes to the curriculum.

Mason City administrators say they had experience teaching some of the books and “ran [the list] by” a librarian after retrieving answers using ChatGPT. But the answers generated by the tool are at times contradictory based on how users prompt and query the software. When The Verge inputted the list of all 19 books banned by the Mason City school district into ChatGPT and asked whether they contained explicit or sexual scenes, the software indicated that several did not contain that content.

Exman told The Verge that the district began assembling the initial list of commonly banned books using sources like news articles and Wikipedia and then whittled it down to around 50 titles that were present in the library’s collection. Exman then tested each of the 50 books once using ChatGPT. Though Exman hasn’t heard from other administrators who are approaching the issue using these methods, other districts have reached out.

“Our intention is to demonstrate a good faith effort to be in compliance with the law without redirecting time and energy that we should be using to focus on getting ready to welcome our teachers and students back for another school year,” Exman told The Verge in an email. “Our goal was to find an efficient process to get the year started with the intention to then rely on our long-standing process that allows parents to ask the district to reconsider. Books that are currently on the list can be reconsidered, just like books that are not on the list can be reconsidered.”