Why doesn't Chris Hansen need permission?

why doesn't Chris Hansen and the show To Catch a Predator need these guys' permission to put them on the show? I keep seeing them telling him as they leave that he doesn't have permission to put them on the show, but they are on it anyway. To me, personally, it doesn't seem like they can do it just because the guys are breaking a law or trying to attempt lewd acts with children. Maybe it's because they feel that people deserve to know what these people look like? But then, couldn't they just show a picture of said man? I'm confused! lol help?