An influential committee of MPs today threw its weight behind the campaign to stop computer hacker Gary McKinnon's extradition to the US.
The Home Affairs Committee also called for a "comprehensive review" of the controversial treaty under which he could be sent for trial.
Mr McKinnon, who suffers from Asperger's Syndrome - a form of autism - faces the prospect of a lengthy prison term for hacking into American military networks.
But committee chairman Keith Vaz called on Home Secretary Alan Johnson to exercise his "discretion" in the case and reject the extradition request.
In a letter to the Home Secretary, Mr Vaz said the committee was concerned there was a "serious lack of equality" in how the provisions of the extradition treaty between the two countries operated.
The Home Secretary is currently considering whether he can decide to stop the extradition on the grounds that it would breach human rights law because of Mr McKinnon's fragile mental state.
Mr Vaz said legal opinion written by senior barristers at Matrix Chambers and seen by the committee suggested the Home Secretary had considerably more discretion to act than Mr Johnson believed.
He wrote: "The committee remains concerned that there is a serious lack of equality in the way the Treaty's provisions apply to UK, as opposed to American, citizens.
"We received a clear legal opinion from Tim Owen QC and Julian Knowles, barristers at Matrix Chambers specialising in human rights and extradition law, that the scope for the exercise of discretion by the Home Secretary is greater than you believe.
"Given the obvious difficulties that have been experienced in applying the Extradition Act and the US-UK Treaty while fulfilling other obligations, such as those under the European Convention on Human Rights, we recommend that the operation of the Act be reviewed comprehensively."
"Because of Mr McKinnon's precarious state of mental health, the committee is of the view that he should not be extradited to the USA and that you should exercise your discretion in this case."
The letter followed an evidence session on Tuesday when the committee heard from both Mr McKinnon's mother, Janis Sharp, and the Home Secretary.
Mrs Sharp told the MPs her son would "rather be dead" than sent for trial.
"We were told this treaty was to be used mainly for terrorists.
"People like Gary are not terrorists. We should stand up to America and say 'This is wrong'."
But Mr Johnson defended the extradition treaty with the US, saying critics treated America like an "enemy state".
In a statement, a Home Office spokesman said: "There is no imbalance in the extradition arrangements between the UK and the US.
"As the Home Secretary told the committee, the evidence that must be provided for a US extradition request to proceed in the UK is in practice the same as for a UK request to proceed in the US.
"The suggestion that the operation of the Extradition Act needs to be reviewed comprehensively is unnecessary.
"The Home Secretary has maintained throughout the proceedings that he has no general discretion to refuse extradition.
"At this stage in the case the sole issue is whether extradition would, or would not, breach Mr McKinnon's human rights.
"Unless the evidence shows that extradition would breach the European Convention on Human Rights it would be unlawful to refuse extradition.
He added: "At present the Home Secretary is looking carefully at the representations submitted by Mr McKinnon.
"The decision will be taken very shortly - not in the exercise of any general discretion, but according to whether extradition would now amount to a breach of Mr McKinnon's human rights."Reuse content