Plenty of unpleasant things lurk online. Bomb-making and bestiality are two of them. Paedophilia, however, is a different matter.
The drive to exorcise paedophiles from the internet has been just as remorseless as the News of the World's campaign to publish their whereabouts - and, to the casual observer, considerably more effective.
Most web hosting companies take down any child pornography they find and report the perpetrators to the home office and the Internet Watch Foundation.
British ISP Demon Internet doesn't tolerate paedophile newsgroups either, and will contact the police if they are found on Demon servers.
Move them on, officer. Fair enough. No one wants to be responsible for harbouring paedophile activity. But cracking down on any illegal vice - whether it is kerb crawling, drug trafficking or paedophilia - tends to mean the trade reappears elsewhere.
Patrick Green chose to use private chatrooms, rather than public websites, to introduce himself to a young girl in the guise of a 15-year-old boy. He then started to email her, enclosing naked photographs of himself.
Green was yesterday jailed for five years in the first such conviction of its kind.
No amount of web policing could have prevented Green from doing this, because the space he operated in was outside the public domain. Just as the law of indecent exposure can only apply in a public place, private chatrooms are beyond the ambit of police surveillance.
The new RIP Bill would certainly have made it easier for police to access his emails once they suspected something, but because Green was impersonating another teenager, scanning for words like "paedophile" would probably have been unsuccessful.
It's easy to report the dodgy-looking character hanging around outside a school to the police. It's even easier to tell the Internet Watch Foundation about a dubious site.
In the same way that children already know why they shouldn't accept sweets and lifts from strangers, perhaps we should tell them why emails can be dangerous, too.
Chatrooms are a kind of online playground. Anyone venturing outside them for a private meeting does so at their own risk.
Useful links
5 years for man who lured girl through internet
