Yesterday, the High Court in London rejected the trio's claims that extradition would breach their human rights. The bankers attacked the use of the Extradition Act of 2003, rushed through in the wake of the 11 September attacks, arguing that it deprives them of the right to defend themselves on English soil, where the alleged crime took place.
David Bermingham, Gary Mulgrew and Giles Darby are accused of defrauding Greenwich NatWest of $7.3m (£4.2m) by investing in one of Enron's notorious off-shore operations. US prosecutors say they worked closely with Andrew Fastow, Enron's former finance chief, and Michael Kopper, his right-hand man, who have admitted their roles in the alleged scheme as part of a plea bargain.
In their ruling, Lord Justice Laws and Mr Justice Ouseley said: "The United States' dimension does not arise from the contingency that a telephone call or an e-mail happened to be received in that jurisdiction. It arises from the close and critical involvement of two senior Enron figures ... It would be unduly simplistic to treat the case as a domestic English affair." They added: "Nor is there anything exceptional about the personal circumstances of these defendants to make a case on proportionality under the European Court of Human Rights."
The case is the first major test of how the new extradition laws, originally designed to fast-track terrorism cases, are applied to those accused of white-collar crime. Hearings in the case of Ian Norris, the former chief executive of Morgan Crucible, who is fighting extradition to the US on price-fixing charges, had been suspended until the High Court's verdict on the NatWest three.
Mr Mulgrew, a single parent with a 10-year-old son, said: "Frankly, we are shocked by the verdict - bewildered. I think this is a worrying verdict ... It seems to be irrelevant that the UK authorities do not believe there is a crime committed against NatWest. Even though we have the victim saying we are not a victim, we are still supposed to go to Texas to defend ourselves."
He said fighting the case in the US would cost up to £1.5m as the trio would need to hire two legal teams and fly 36 witnesses from Britain to Texas. The men could face up to 25 years in prison if convicted.
The NatWest three, all aged 43, will now appeal to the House of Lords and might take the case to the European Court of Human Rights. That means the legal battle, which started in 2004, threatens to drag on for several more years. The House of Lords would not hear the case until the autumn or early next year.
The extradition laws have been attacked by business leaders and human-rights lawyers, who have dubbed them "extradition on demand". US authorities are not required to present a prima facie case.
The director of the human-rights group Liberty, Shami Chakrabarti, who attended court with the trio, said the Extradition Act was "nothing short of a disgrace".