A public charter school is suing Idaho officials after they barred the school from using the Bible.
An Idaho state school commission had earlier ruled the school could not teach students about the Bible.
Nampa Classical Academy said it wanted to teach students about the Bible's influence on literature and history - not to give instruction about religion.
The Alliance Defense Fund (ADF) represented the school.
"The Bible shouldn't be singled out for censorship," said ADF Senior Legal Counsel David Cortman. "Not only is the commission on safe constitutional ground to allow the school to use the Bible as an educational resource, it would be unconstitutional to deny the school the ability to include it as one resource among its many other texts."
Cortman argued that the commission's ruling is based on a misinterpretation of a provision in the Idaho Constitution.
"That provision does not forbid the Bible from being included as part of a public school's curriculum. On the contrary, the framers of the state constitution sought assurances that the right of public schools to use the Bible as a teaching tool would be protected," Cortman said.
The ADF asked the commission to protect the right of public schools to use the Bible as a teaching tool.
But the Idaho Public Charter School Commission ruled that the state constitution limits the use of religious texts and plans to abide by its ruling.