A British computer expert accused of hacking into US military networks would be at real risk of psychosis or suicide if extradited to America, the High Court was told today.

Gary McKinnon, 42, faces a lifetime in jail if he is found guilty in the US of sabotaging vital defence systems after the September 11 terror attacks.

But his supporters say that he acted through “naivety” as a result of his Asperger’s Syndrome - a form of autism - and should not be considered a criminal.

Edward Fitzgerald, QC, appearing for Mr McKinnon, told the High Court his medical condition was likely to give rise to psychosis or suicide if removed to the US, far away from his family, and he should be allowed to stand trial in the UK.

The QC said: “The very fact of extradition will endanger his health.”

The chances of Mr McKinnon’s health being endangered were further increased by the real risk that he would be detained pre-trial in tough conditions in an American high security prison, violating Article 3 of the European Convention on Human Rights protecting against inhuman and degrading treatment.

Mr Fitzgerald accused the Home Secretary, Jacqui Smith, of failing to inform herself and properly consider these risks before deciding in October last year to permit extradition.

He said she had also failed to request an undertaking from the US that Mr McKinnon - “a seriously disordered person” - would be repatriated to serve his sentence in the UK.

The QC argued there was a reasonable suspicion that the repatriation issue was being used as “a bargaining counter” and there was “the sniff of abuse about that”.

Lord Justice Maurice Kay and Mr Justice Simon, sitting in London, were asked to grant the hacker permission to seek judicial review of the Home Secretary’s extradition decision.

Government lawyers argue that the move to extradite does not infringe either Article 3, or Mr McKinnon’s Article 8 rights under the European Convention to private and family life.

The judges refused a request for an adjournment of the hearing while Keir Starmer, QC, the new Director of Public Prosecutions, considers a request for Mr McKinnon to be prosecuted in Britain on a lesser charge.

Mr Fitzgerald told the court the Home Secretary had already agreed not to extradite pending the director’s decision.

Mr McKinnon, from Wood Green, north London, insists he was only looking for evidence of UFOs when he hacked into the US military networks in 2001 and 2002.

He has signed a statement accepting that his hacking constituted an offence under the UK’s Computer Misuse Act 1990.

But the US military alleges that he caused 800,000 dollars-worth (£550,000) of damage and left 300 computers at a US Navy weapons station unusable immediately after the September 11 atrocities.

Mr McKinnon is accused of hacking into 53 US Army computers and 26 US Navy computers, including those at US Naval Weapons Station Earle in New Jersey, which is responsible for replenishing munitions and supplies for the Atlantic fleet.

He is also accused of hacking into 16 Nasa computers, one US Department of Defence computer and one machine belonging to the US Air Force.

Mr McKinnon was caught in 2002 as he tried to download a grainy black and white photograph which he believed was an alien spacecraft from a Nasa computer housed in the Johnson Space Centre in Houston, Texas.

He was easily traced by the authorities because he used his own email address.

At a press conference last week Mr McKinnon said he believed he would get a fairer trial in the UK than in America.

He also admitted to being “extremely stressed”, adding: “I am very controlled, which is probably not a good thing, but inside the fires of hell are burning. It’s not a good place to be.”

The judges reserved their decision on whether to grant permission to challenge the Home Secretary.

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