Make it a policy, not a law. Maybe I just don't know, but it sounds like security would be weakened if there was some form of monitoring service, and that just a blanket list or word searcher would end up dragging normal sites along with it. Oh! And cell phones have internet access these days I've heard... so I expect they can just use those at work if that's what they do. So you'll spend a ton of money because one guy looked at porn and it just means he will use his phone, or iPad, or personal laptop, whatever.