Quick soalan about Harry Potter and the Goblet of api, kebakaran (Movie): **Contains spoilers if not seen movie atau read book**

First of all, I don't think the Unforgivable Curses are illegal atau that something will happen to anda if anda do one of them. Its just..well unforgivable. Now its Moody in disguise, he himself is an auror so he can use it whenever he wants. Keep in mind that the student doesn't know if its illegal so they can't tell Dumbledore atau any other professor.

Good question. Yes those curses are illegal. However, Dumbledore has always done things his way. That scene is in the book and the movie. If anda recall from Order of the Phoenix (book), Dumbledore hired Firenze as a Divination teacher after Umbridge sacked Trelawney.
Most likely, no one did anything because no one at the Ministry knew until probably that summer. Dumbledore knew the whole time. He's the one that wanted "Moody" to tunjuk the kids those curses. Reread that scene in the book. It's the chapter headedby a picture of Moody.

Because the kids where to scared to tell him. Even if they did who would believe them?!

Dumbledore gave him the permission to

Yeah, Dumbledore was the one to tell Moody. And the students did know.. I believe it was dikomen (by Hermione, probably), that they were illegal, and that Moody could have been imprisoned.

It's illegal to use the spells on human beings, not to teach about them (or use them on spiders). The only one Fake Moody actually used on the class was the Imperius Curse, when teaching them to throw its effects off. Hermione did initially soalan the legality, but Fake Moody berkata that Dumbledore had telah diberi him permission and that it'd be better that they get the practice even if illegal.