An American judge will have to balance Constitutional rights with the protection of gay kids at school in a lawsuit about the phrase “that’s so gay” that has come before the courts.

A Mormon high school student in the United States used the phrase, was given a warning for doing so by school authorities, and now her parents are suing.

They claim the word is youth slang meaning stupid, silly or dumb, and that their daughter was not protected from teasing about her Mormon faith.

The case raises wider issues about the use of the word gay in popular culture.

In the UK, BBC Radio DJ Chris Moyles caused outrage last year for using the word in its slang context on his radio show.

The high school at the centre of the American court case say that they have a zero tolerance policy to sexual orientation abuse after violent incidents against a gay pupil.

“The district has a statutory duty to protect gay students from harassment,” the district’s lawyers said in a legal brief, according to indystar.com

“In furtherance of this goal, prohibition of the phrase ‘That’s so gay’ . . . was a reasonable regulation.”

The pupil at the centre of the case, Rebekah Rice, testified last week that she only used the word to deflect rude comments about her religion and only meant it in the slang sense. Her parents claim she has a right under the First Amendment of the US Constitution to free speech.

Superior Court Judge Elaine Rushing of California will take written submissions from both sides in April.

In the UK, research by the National Union of Teachers last year revealed that the vast majority of their members hear the word gay used pejoratively on a regular basis.

Many felt that sexist and homophobic language was institutionally tolerated.

The NUT’s “snap survey” found that nearly one in five primary teachers and two-thirds of secondary teachers have been subjected to sexually abusive language by pupils.

Almost 75% of secondary teachers and 30% of primary teachers have encountered such language being used by pupils against each other.