Is it alright for a teacher to ban a book?

I’m 12 and LOVE reading- especially John Grisham novels. But my teacher doesn’t allow us to read any books that are no in the Lexile program, because she’s too lazy to mark quizzes. Long story. But at the end she allowed people to read what they want, except me. Ms. Swan banned Grisham. I find it stupid, since Ms. Pynes, the deputy principal said I could and should, but Swan doesn’t allow it. The worst part is, The Hunger Games is more violent and not for my age, though I find Grisham SO much!!!!! What should I do? I HAVE talked to my teacher.Thanks;):)