It is not altogether surprising that the High Court decided yesterday to allow the extradition of the former NatWest bankers David Bermingham, Gary Mulgrew and Giles Darby to the US to face trial on fraud charges. That is the logic of the Government's Extradition Act 2003. Bad laws lead to strange decisions. This case is particularly strange, and the law is draconian and lopsided.

The three British bankers are accused of defrauding NatWest, their former employer, by persuading it to sell a stake in another company to Enron. If that is the case, they should pay. Yet NatWest has never brought charges. Nor have any of the relevant UK authorities: the Crown Prosecution Service, the Financial Services Authority and the Serious Fraud Office. The irony is that the three men could not have been extradited if a trial had taken place in Britain, because of the double jeopardy rule.

Zealous US authorities seem to have decided some time ago that they wanted to add these British scalps to those they have already taken after prosecutions associated with Enron. It is not clear whether they have in their possession additional evidence that the British authorities did not hold. If there was any additional evidence — perhaps from former Enron executives who have been cutting deals with prosecutors — the British Government should surely have requested it. But that aside, the most worrying aspect is that they do not need any evidence for extradition to go ahead.

The case exposes the weakness of the 2003 law that was put in place to facilitate extradition of terrorist suspects after September 11, 2001 — and which has apparently been used to request the extradition of almost as many executives as putative terrorists. It absolves the US of the need to prove that there is a prima facie case to answer. This means that the US can extradite virtually on demand: it no longer needs to prove that a citizen has committed an extraditable offence.

The way in which the three bankers have handled the proceedings is not altogether attractive. Nevertheless the essentials of the case are clear: they are British citizens who are alleged to have defrauded a British company primarily on British soil. The matter should have ended there. Yet the High Court yesterday rejected the argument that UK citizens should be prosecuted in England if the alleged criminal conduct occurs mainly in the UK. This sets an alarming precedent for all honest business people involved in transatlantic deals. The apparent arbitrariness of this law will do nothing to change the popular and generally misguided view that American justice is fundamentally flawed.

The legislation is also grossly unfair because it is one-sided. Britain must still provide the United States with evidence of “probable cause” if it wishes to extradite someone to Britain. That is nonsensical. Extradition treaties should be fair, and reciprocal. They should have a clear and consistent logic to them or else they will be discredited. Whatever the innocence or guilt of the NatWest Three, this is not the way for justice to be done.