BOISE, Idaho — Idaho Gov. C. L. “Butch” Otter vetoed legislation Tuesday that would have expressly permitted the use of the Bible in public school instruction, calling the measure unconstitutional.

“I have deep respect and appreciation for the Bible as religious doctrine as well as a piece of historic literature,” Otter wrote in a letter accompanying the veto. “However, allowing S1342 to become law is a direct contravention to the Idaho Constitution and it could result for the loss of funding and costly litigation for Idaho public schools.”

Idaho public school students are already allowed to reference the Bible and other religious texts in their studies, but the rejected legislation specifically mentions the Bible, stating the book could be used for reference purposes in subjects such as literature, history, music and world geography.

State lawmakers passed the measure in the final week of this year’s session, after ignoring a warning from the attorney general’s office that questioned its legality.