That's state law, not Internet law
Seriously though, let's consider that if you're a personality/celebrity or product on Facebook then by placing yourself / your product on Facebook, you have implicitly agreed to see any publicly posted material.
As per their TOU:
Whenever you allow an App on Facebook, you have to agree to certain permissions. While it certainly doesn't explicitly say "We can post on your wall any time we want", it does state for example when an app wants access to post to your wall, access your friends list, or requires offline access (the offline access one is the tricky one that allows apps to post to your wall et al without intervention from you). You can go to your app settings and remove any app you no longer want to allow access to your account, and when you are in the process of allowing an app access, you can usually remove individual permissions as well.