Teenager Brittney Settle said she wanted to write about Jesus, but the teacher told her to think again, reportedly saying there was only one source: the Bible.

Brittney wrote the paper anyway. She failed, and her father sued. The Supreme Court this month rejected the family’s claim that it was infringement of her rights of free speech. But the Settle case and others like it have become a cause cel bre for the religious Right.

Their activists are now seeking to rally support for an amendment to the US Constitution to prevent discrimination against the expression of religious views, by schools or other public bodies.

The US doctrine of the separation of church and state, and its strict interpretation by the courts since the Second World War, has banned virtually all religious activity in schools. It has been a constant source of tension in a mainly Christian country where religious observance is much greater than in Europe, particularly in states with active communities of fundamentalist and born-again Christians.

Conservative Christians claim there are many cases, like Brittney’s, where people have been barred from simple expression of their religious views.

Gregory Bayler, of the Christian Legal Society of Annandale, cites the girl who was forbidden to use part of her graduation speech to talk about the role of Jesus in her life, and school districts in several states have banned pupils from even distributing Bible study leaflets outside their school gates.

One fifth-grade teacher was allegedly barred from having a Bible on his desk or reading it when the students were reading.

Michael McConnell, a professor of constitutional law at the University of Chicago, framed the religious discrimination amendment. It is seen as a milder alternative to long-running and controversial demands from the religious Right to legalise and reintroduce school prayer.

“The current legal framework is a complicated environment for US school authorities,” he said.