GREENSBORO, N.C. —  Traditionally, witnesses taking the stand in court are sworn in by placing their hand on the Bible (search).

But when Muslims in Guilford County, N.C., tried to donate copies of the Koran (search) for courtroom use, judges turned them down.

Chief District Court Judge Joseph Turner (search) says taking an oath on the Koran is not allowed by North Carolina state law, which specifies that witnesses shall place their hands on the “holy scriptures,” which he interprets as the Christian Bible.

“We’ve been doing it that way for 200 years,” he said. “Until the legislature changes that law, I believe I have to do what I’ve been told to do in the statutes.”

But the Council on American-Islamic Relations (CAIR) and the American Civil Liberties Union are challenging the Guilford County Courts.

“This was the first time that we had a judge … going on record and stating unilaterally what is a holy scripture and what is not — what we believe to be a violation of the establishment clause,” said Arsalan Iftikhar of CAIR.

Their case is solid, according to one Duke University (search) law professor.

“I have absolutely no doubt that higher courts, if it gets there, will say that persons of Muslim faith can swear on a Koran rather than a Christian Bible,” said Erwin Chemerinsky. “The case law is so clear here that a person doesn’t even have to swear on a Bible to be a witness so long as they’re willing to promise to tell the truth.”

Click in the box near the top of the story to watch a report by FOX News' Jonathan Serrie.