The teacher shouldn't single you out in front the entire class, especially based on the fact that your the guy's best friend... I do believe that kind of sh** is actually illegal in the US.
No, there is no "law" that states it in those exact words, but there are certain regulations that all schools and teachers in the US have to abide by, especially in disciplinary situations. They cannot single you out in front of the whole class like that.
I know a lot about the regulations in the US system because my mother was involved with an agency that helped parents with legal matters involving disciplinary actions in schools. Plus, I was in similar situations as the one you described a few times. I basically just said "Legally, you can't do this." That really pisses them off... They don't like when students know their rights and aren't just the teachers puppets to manipulate.
Since I don't know the regulations of your particular country, I couldn't say, but I would do some research into that if I were you.
