> What happens if I put a blanket ban in the TOS on use of the site by anyone acting as an agent of any law enforcement agency? Certainly with a warrant, it would hold up , but without one, it may not.

Actually, I'm not so sure you don't have that backwards. If a police officer shows up at your door without a warrant, you can tell him "hey, no cops allowed in my house!" and make him leave. But he or she has a warrant, you can deny them all you want, but they're legally entitled to come in and look for stuff.

With a login page, it would work roughly the same way. "No cops allowed" might work, but not once a judge gives the police a right to be where you don't particularly want them.

I think the point is: all that was one WITHOUT a warrant...