Banned books and movies

In the 21st century, trying to ban a book is, arguably, futile; the result of a ban may just be the opposite of what's intended. Even though there exist authoritarian regimes where it's technically possible to block access to information, -- whenever one country bans some work, it will only bring heightened attention to that work everywhere else, it will only raise its profile in the rest of the world.

Instead of banning something, it is more effective to ignore it, to pretend that it doesn't exist or at least that it doesn't deserve to be mentioned.

What would it take, nowadays, to get a book banned (in North America or Europe), or at least to get the authorities to try to suppress it? (Aside from the obvious, such as: the kind of material that the vast majority of the population would find offensive and distasteful.)