Providing access to porn is not a librarys business.
Nor is it a library's business to define what qualifies as pornographic.
Bingo.
Of course, the optimal solution to this entire 'problem' would be for there to public ownership of the Internet backbone and allowing low income families free or reduced access, but that's rather unlikely, given that the Internet has become laissez faire's greatest frontier ever.
...because lack of access to pornography is one of the great injustices facing the poor? I'd be more concerned about, oh I don't know, their kids being able to access sources to write papers for school and stuff.
Poll
