There are a lot of good points in this post, especially the ones about different kinds of censorship. Unconscious censorship and censorship due to a fear of being challenged are very common, especially in schools and public libraries. I agree that this is still a serious form of censorship and should really be avoided. There are particularly a lot of manga and graphic novels that are deemed inappropriate for teens or even libraries as a whole, simply because of a fear of being challenged in the future.
Top Ten Things You Need to Know About Banned and Challenged Books