Students at a public school in Fremont, Nebraska, have been told they can't wear a rosary to school because it's also considered a gang symbol.
Elizabeth Carey, 12, told Omaha television station KETV her elementary school adopted the policy last year.
"The principal said I couldn't wear my necklace at all because gangsters were wearing it," she said.
Superintendent Steve Sexton told the television station the policy is for student safety.
"We had information from law enforcement that there were documented instances of gang activity in the area and we had information that states that the rosary was being used as a symbol of gang affiliation," Sexton said.
But the move has raised the ire of the American Civil Liberties Union of Nebraska.
In a press release entitled, "That gang of nuns looks pretty dangerous," the group says the school's policy raises "seriously concerns about children's religious liberty."
The group also says it violates the First Amendment right to practise religion freely.
"Students have the right to express their faith in public schools. Whether a student wants to wear a crucifix, a rosary, or another symbol, it is wrong for school officials to interfere. We understand the serious concerns about gangs in schools, but Fremont Public School should demonstrate there is a concrete gang connection before shutting down a student's free speech and religious rights," ACLU Nebraska legal director Amy Miller said in a statement.
Carey said she will continue to wear clothing that shows her religious views.
"I'm deciding to stand up for Jesus and do whatever I can to stop this," she said.