The American Civil Liberties Union has filed a lawsuit over a prom which was cancelled because of a lesbian student.

Constance McMillen, an 18-year-old student at Itawamba Agricultural High School, was barred from attending the event in a tuxedo and with her girlfriend.

When she complained, the school decided to cancel the event, making headlines around the world.

The ACLU, acting on behalf of Ms McMillen, has now filed a lawsuit in federal court against the school, claiming it violated her First Amendment right to freedom of expression.

The lawsuit seeks legal fees, nominal compensation of $1 and a court order requiring the original event to go ahead.

The student was told she would have to wear ‘female’ clothes and could not arrive with her girlfriend. She was told that if the couple danced together or made other students uncomfortable, they would be thrown out.

Last week, Ms McMillen told the Clarion-Ledger she feared she would have to move schools over the controversy.

She said: “That’s really messed up because the message they are sending is that if they have to let gay people go to prom that they are not going to have one.

“A bunch of kids at school are really going to hate me for this.”

The gay and lesbian group Mississippi Safe Schools Coalition has announced it has raised enough money from supporters to hold another prom welcoming all gay and straight-ally students.