When Alex Stone logged onto a chatroom for the blind three years ago, he little realised he was unleashing a chain of events that would see him extradited to America in handcuffs and shackles on a maximum security private jet.

Stone, 34, has just returned from the US, having spent more than six months in jail on remand before an assault charge against him was dropped. Worryingly, he was extradited under laws set up to deal with terrorists that mean America can in effect remove a UK citizen from British soil “on demand” without having to prove there is a valid case.

He is now joining 150 MPs being mobilised by the Tory frontbencher Boris Johnson in a campaign to overturn the 2003 Extradition Act, which has also been used to try to extradite the three British businessmen accused over the collapse of Enron.

The law replaces the age-old rule under which American prosecutors had to show there was a prima facie case when asking British courts to extradite. British courts do not have the same power to extradite American suspects, as that would break the terms of the American constitution, which demands that the requesting country shows “probable cause” that the proposed extraditee is guilty of the crime in question.

Ironically, the treaty was signed by Britain’s blind home secretary, David Blunkett.

The problems began when Stone, who has been blind from birth, met 20-year-old Alma — from the incongruously named Liberty, Missouri — on www.blindkiss.com in 2003, which proclaims it “explodes the notion that being blind is some kind of living death”.

“I suppose I was kind of lonely,” says Stone, who returned to Britain 12 days ago. “She was lovely, really fun, and we got on so well.”

They began to talk on the telephone and, in August 2003, Stone went to stay with Alma and her young child from another relationship. “We had so much fun,” says Stone, from Tooting, south London. “We had fallen in love. We were talking about marriage.”

Stone decided to move to America to be with Alma. Two weeks after he arrived, however, her 14-month-old child was taken to hospital and found to have suffered broken bones.

“It transpired that the family and the local police decided that it must have been me who had done it.” He was advised by his American lawyer to return to Britain, because he had not been arrested or charged with a crime.

Naively, perhaps, Stone, who has no previous convictions, hoped this would be the end of his matter. Estranged from Alma, who would not speak to him, and nursing a broken heart, he tried to fit back into his old life as a computer programmer, contacting a British lawyer as a precaution.

“I knew that I had not harmed the child, and I imagined that in order to be extradited somewhere, there had to be some burden of proof,” he says. But in November 2004 he was horrified to discover that British police were looking for him. He turned himself in and was extradited under the new laws after three hearings at Bow Street magistrates’ court.

“There appeared to be no defence to extradition and no evidence at all was presented,” he says. “I had thought that would be a requirement. When I realised what was happening, I was really, really scared.”