That's my understanding too Dave O. But maybe Richard Bridge will revisit the thread and provide a more authoritative view.

Extradition from one country to another is usually governed by bilateral agreements, and these are usually reciprocal. Where no treaty is in place there is usually no extradition, though one-off exceptions do occur. The problem with the US-UK treaty, Joe, is that it provides for extradition from the UK to the US in more circumstances than vice versa. The general opinion seems to be that in this particular case, the treaty would not require US-to-UK extradition if the alleged crime had been committed by an American in the US.

There is concern in the UK that the US authorities regard McKinnon's crime as far more serious than it has been regarded in the UK and that any sentence imposed might be disproportionate. I have seen it claimed that McKinnon could be jailed for anything up to 70 years. There is also concern that the US judicial system would make little allowance for his mental state (there is medical evidence, uncontested as far as I have seen, that he has Asperger's syndrome).

An acquittal is unlikely whether he is tried in the US or UK court, sincce McKinnon has admitted throughout that he hacked into the Pentagon system. He even left messages on the system admitting he had been prowling around, to warn that the system was vulnerable. But it is assumed on both sides of the Atlantic that he could expect a more severe sentence in the US than in the UK (where he committed the crime of course).

Thanks, Joe, for changing the title,