The very idea that you can effectively be transported to a country that you have nothing to do with and committed no crime in just purely because the big boys with the big wallets say so is sickening.
His website was accessible in the US by design (one could forbid US visitors in the ToS, and by geoip), and the "harm" from his supposed crime occurred, for those US users, in the US, not inside his server.
What sucks about this case is that it seems incredibly unlikely that linking constitutes a felony copyright infringement, because no copyrighted material is ever directly encountered. It seems much more likely that only a misdemeanor infringement occurred (if any), for which the UK does not extradite to the US.
No one should have to concern themselves with the laws of every nation on Earth when building a website. There is usually not enough time in your life to consider the laws from only your home country.
If you run a dubious website, your only option is to block all countries other than your own, and provide a notice to that effect.
Is it silly? I dont know. It's hard to argue that you have the right to interact with a country's inhabitants but that the country cannot govern those interactions. Though the governing needs to be fair...
Of course, if a crime is only half-committed in one country, then it is also only half-committed in the other country (presuming it is a crime in both). So either of the countries must be free to prosecute.
Have you allowed people to upload stuff to your website and didn't stop them enough? Well, it looks like you're liable for conspiracy for copyright infringement of something. A criminal penalty of $150k and 5 years jail per infringement.
Oh, it looks like you did it to several copyrights. That's a jailin'. Who cares if you haven't visited USA before! Like that ever stopped USA: https://en.wikipedia.org/wiki/Hew_Raymond_Griffiths
As a British citizen I'm truly sickened by the idea that someone can be extradited over something which is potentially not even a crime, when the biggest name in the game is still sat with million dollar legal teams ready to pounce if they get pulled up on it.
However, the "Google do the same" argument doesn't fly, because Google follow the DMCA and so are exempt from being prosecuted for any copyright infringement from user-generated or crawled content.
PS - "harm" is a very general concept, so if I facilitate copyright infringement in the US from the UK, the "harm" occurs in the US, even though I'm in the UK.
Does anybody have any legal specifics here? I wonder if this is something that could happen to just random bittorrent users?
For example, this would not be possible in France (i live there) as the country never extradites any of its citizens for any reason - this will stand even if you committed a crime abroad and managed to get back, you could only be tried back home -
As for the british kid, I support him 100% but it seems that the UK has signed very liberal agreements with the US concerning their citizens...
NB It's not just France that has this policy:
http://en.wikipedia.org/wiki/Extradition#Bars_to_extradition