Why was Tropic of Cancer banned?

I have read the whole book and I didnt find much bad about it. It was very sexually explicit, but sex is natural and normal =/ I have to write two papers on why it was banned. One has to be about "why it should be banned", the other one has to be about "why it should not be banned". I need help =/ I have half a page each done already, I'm just running out of things to say on why it should not be banned. Help please =/