Several years ago, overwhelming majorities in the US Senate and the House passed a bill barring US aid to countries that refuse requests for extradition ... American requests that is. The only concern voiced was that the bill would theoretically bar aid to the US client state of Israel because of its refusal to extradict a man charged with a murder in Maryland in 1979, I think. The man, I can't remember his name; will have to look it up, had fled to Israel and claimed citizenship thro' his father. It seems like the US treats its client states differently.
If the man has broken the laws of the United Kingdom, which he probably has, then he should be tried in Britain. And if found guilty, he should serve whatever time he is given in a British jail. I still believe that the "cruel and unusual punishment" argument applies.
And for those who seem to think that the admittedly tough US prison system works, look at the crime rate in that country. And, incidently, consider such questions as: Why is it that one in five of black American males is, or has been in, the US prison system.
And before I shut up and head off to the fridge for a beer, the US routinely sends convicted Canadians back to Canada to serve their sentences. Not in all cases, but enough. Betcha Conrad Black wishes he hadn't given up his Canadian Citizenship.