You can’t insult your teacher in class – but can you on Facebook?

If you call your teacher a "douche bag" and "fat ass" in class, that constitutes bullying.

But if you do it on your own Facebook page after the bell rings? Well, nothing wrong with that, according the American Civil Liberties Union.

A grade 10 student in California who referred to his teacher as a "fat ass who should stop eating fast food, and is a douche bag" in a Facebook post – apparently in reaction to getting a large pile of homework – was suspended from school in December after someone who saw the post reported it to administrators, reports AllFacebook.com.

But the ACLU – a U.S. charity that promotes free speech – has come to the student's defense. After learning about the incident, ACLU attorney Linda Lye wrote a letter to the school, asking it to reverse its decision to suspend the student.

She argued that the student's post did not constitute cyberbullying because it did not "materially or substantially [disrupt] the school environment." Also, he posted the status update from home during non-school hours.

This isn't the first time the ACLU has come to a student's defense in such a case. Last year, it took a school to federal court for suspending a student who created a Facebook page that referred to her teacher as "the worst teacher I've ever had." The student won a settlement and had the suspension expunged from her record.

But in a similar case last fall, a student at a New York middle school was suspended for creating and posting "obscene" messages about a teacher on a Facebook fan page. More than 20 other students were given detention for being fans of the site.

In that case (which the ACLU did not involve itself with), the group was public, whereas in the recent California case, the post was on one student's (technically) private Facebook wall.

These cases raise some big questions about online posts related to teachers. What constitutes cyberbullying? Is it the content, the time or the forum? Or all three? Is calling a teacher "the worst" acceptable on a review site such as ratemyteachers.ca?

Share your thoughts in the comments.