"Why couldn't he be arrested and tried here in the UK - his home."
In the UK there is an element of plea bargaining, for instance the prosecution may accept a guilty plea to manslaughter to avoid a lengthy murder trial that may just result in the same verdict. We also have a system of fixed penalties for minor criminal offences such as speeding (but not too fast).
What we don't have is a way to offer a very low level punishment for a guilty plea against the possibility of 50-150 years imprisonment for an unsuccessful not guilty plea. The nominal discount for an early guilty plea is one third off the sentence. This case will be difficult to explain to a jury, the judge may not understand and the jury may just want to set him free because he "saved the NHS." The trial will take a long time and may not result in a conviction. However the US court system seems to think that, in order to get around this awkward situation, it is acceptable in a mature, liberal democracy to make on offer you can't refuse.
Biting the hand that feeds IT
