Can someone explain to me this Nat West 3 case

I must be missing something somewhere.

As I understand it the US alledge that the 3 men defrauded their employer (The British National Westminster bank in England) by advising them to sell its stake in a part of Enron at below market value. Subsequently they left the bank and bought shares in the unit and made money when the shares increased in value again.

Now I dont know whether the men acted illegaly or not, but surely if they did the offence was comitted in the UK against a UK company. The fact that the traded stock was a US company is surely irrelevent.

In any case this has been investigated in the UK and it was decided there was no case

My understanding is that in our country the following applies.

It is now possible to remain in the UK and act in a way that breaks no UK laws
The US can then decide that you might have broken one of their laws
The US authorities only need to say that if you were in the US you would be arrested so please send the "criminal" over and we say OK get on the next plane.

Of course no such arrangement operates in reverse

Am I missing something or is it really that barmy?