r-indent = American teachers are increasingly reluctant to speak freely in school following several recent judicial decisions.
Separate courts during the summer upheld school board decisions to fire a St Louis writing teacher for allowing students to use expletives in their work while a Colorado high-school teacher lost his job for showing his class Bernardo Bertolucci's film 1900.
Now the US Supreme Court is considering whether to hear the case of a North Carolina drama teacher who was transferred for producing a play in which one character was a lesbian and another pregnant out of wedlock.
"It's surprising that we still don't have any definitive statements on teachers' rights of expression," said Jay Heubert, associate professor of education at the Teachers' College of Columbia University and an adjunct professor of law.
"Without a clearer understanding of the rules," he said, "teachers would walk around perennially in fear that anything they might say that could be objectionable to anybody could be the basis for disciplining them. And if you want dynamic, imaginative, experimental teachers, you simply can't put them in a situation when they're in constant fear."
But teachers clearly are afraid. After the St Louis teacher was fired for allowing her students to write and act out plays in which some used profanity, a colleague excised all the "damns" and "hells" from a student production of the musical Oklahoma.
The only definitive decision from the Supreme Court about free speech in schools was in 1988. In Hazelwood School District vs Kuhlmeier the justices affirmed a school administrator's right to review a student newspaper before it was distributed.
With no other guidance, lower courts have used the logic of the Hazelwood decision in cases involving speech by teachers. If a school can control a newspaper written by students, they have reasoned, then it can restrict the classroom behaviour of a teacher.
Still, the Supreme Court has never explicitly said that Hazelwood applies to teachers' speech. That would change if the justices agree to hear the case of Margaret Boring, the North Carolina drama teacher whose controversial play was condemned by local church ministers.
Ms Boring sued after being transferred to another school, charging that school officials violated her right of free speech guaranteed by the First Amendment of the US Constitution.
A federal court dismissed her complaint, and she appealed to the Supreme Court.
"In the world at large, individuals have fairly broad free speech protections," Dr Heubert said. And "if you think of schools as being training grounds for future citizens and you agree with the values of wide and robust debate, that doesn't happen if teachers have to walk around afraid."