I'm the former owner/operator of ww.com, in its day a pretty large video streaming community, think 'twitch' but many years earlier. We had fairly regular contact with the police to ensure that our members were operating within the law, and some of them repeatedly decided to test where the line was. As responsible operator of a large web property you are an extension of society and society has - fairly universally - come to the conclusion that having a police force is both useful and necessary. As a forum operator you can choose to go head-to-head with the authorities or you can choose to work with them, we - just like Twitter - chose to do the latter because we believed that this was in everybody's best interest.