Lord Lloyd of Berwick, a crossbench peer and former law lord, has questioned the Government's decision to intervene in the Gary McKinnon case.
If a suspect can be prosecuted in two or more countries the essential question is where he can best be prosecuted. That is where he is most likely to be convicted if guilty.
In almost every case that would depend on where the bulk of the evidence would be. That is a question best decided by the prosecuting authorities in the two countries involved and not by Parliament.