Controversial content can be legal in one country, while illegal in other countries. I know a Dutch website that gives hooker reviews, while another gives Amsterdam coffeeshop reviews. All perfectly legal in The Netherlands where these sites reside, but probably illegal under US law. I think there must be plenty examples of controversial content thats legal within specific areas. Plus: its virtually impossible to know exactly what has been posted on your forums. Unless you approve each post, before it becomes visible. But try that on a busy site.