Supporters of Gary McKinnon have condemned the decision to let the former hacker be extradited to the US.
Mr McKinnon's fight against extradition has lasted four years
On 4 July Home Secretary John Reid granted the US request to extradite Mr McKinnon for trial.
One friend of the hacker said he was being made a "scapegoat" for the shortcomings of security policies on US military networks.
Others said the potential sentence he could serve if found guilty was out of proportion to the crimes he committed.
Dr K, an author and chronicler of the hacking scene, said he was "saddened" by the news that Mr McKinnon could be extradited.
"The US Government is scapegoating Gary McKinnon to cover up their own shortcomings as systems administrators," he told the BBC News website. "Who breaks a butterfly on a wheel?"
"It's a decision long on spin and short on substance," he said.
Extraditing and trying Mr McKinnon would do nothing to improve security on US military networks, he added.
Mr McKinnon has never denied that he wandered around the computer networks of a wide number of US military institutions between February 2001 and March 2002. Mr McKinnon was arrested in November 2002.
However, he has always maintained that he was motivated by curiosity and that he only managed to get into the networks because of the lax security on these systems.
Many of the messages left on the "Free Gary" blog, which has been supporting Mr McKinnon's campaign to fight extradition, criticised the Home Secretary's decision.
One supporter said the decision was "disgusting" and another said it set a "terrible precedent".
Others said hackers and other hi-tech vandals should be punished for their crimes, but questioned whether Mr McKinnon's treatment had been "fair" as so far the evidence presented by the US against him had not been contested in court.
Slightly more than 50% of 500 IT professionals polled online by computer security firm Sophos said that Mr McKinnon should not be extradited to the US.
A decision in the case was originally due in February 2006 but was postponed as the UK sought assurances from the US about some issues in the case.
The UK wanted to be sure that Mr McKinnon would not face a military tribunal, will be eligible for parole and that he would not serve his sentence at Guantanamo Bay.
Once the judge in the case had these assurances he agreed to let Mr McKinnon be extradited.
Mr McKinnon now has 14 days in which to appeal to the High Court against the decision to extradite him to the US.
He faces decades in jail and millions of dollars in fines if found guilty during the trial that would result from his extradition to the US.