The extradition of the Pentagon hacker Gary McKinnon seems almost certain now that the high court has dismissed two claims for judicial review. The only person who can save him is the home secretary, Alan Johnson, and on current form it seems unlikely that he will prevent McKinnon being taken to the states to face a penalty of up to 60 years in jail.

The issues here do not turn on McKinnon's guilt; he admits that he broke American law by hacking the computers belonging to the US army, US navy, US air force, department of defence and Nasa and leaving messages in their databases. Rather they concern his mental condition and the unacceptable inequity in the extradition arrangements between the US and Britain.

The 2003 extradition treaty, made at the height of the "war on terror" to facilitate the rapid conveyance of terrorists to US courts, means that suspects in America are 20% less likely to be extradited to Britain than Britons are to America. The law is a product of its time and of Tony Blair's hopeless infatuation with George Bush. The checks and balances built into the system to protect British defendants were swept aside with the government's usual contemptible lack of regard for individual rights, justice and proportionality.

Since the act became law in 2003, just one terrorist has been extradited while over 55 British defendants have been forced to submit to the often crude and vindictive criminal justice system of the United States. Sixty years for a rather hopeless individual who believes in UFOs is obviously absurd, and British law should have the ability to ensure that a citizen is not exposed to harsher treatment in America, then Americans accused of the same crime would face here.

Labour's failure to support that principle in a vote for the review of the treaty – just 10 Labour MPs voted for it – was responsible for Labour MP Andrew MacKinlay's announcement that he had decided to stand down at the next election. It is difficult not to share his disdain for the governing party: not only is it responsible for this shoddy law, it will take no action to correct a glaring injustice. "It's not only his extradition, which is unfair, but this treaty has been implemented by the government without proper discussion in parliament," MacKinlay said. "Many of my colleagues expressed sympathy with Mr McKinnon, but they allowed themselves to be dominated by the party whips.

This is one of the deficiencies of parliament."

Over 100 MPs of all parties have campaigned against the treaty and McKinnon's extradition, and the Daily Mail has waded in with a very effective campaign, yet the government remains heedless of the desire to see fairness and equality returned to our legal relationship with the US. It is ludicrous that American prosecutors have only to supply details of a charge to a British magistrates court to trigger extradition, while British lawyers have to provide evidence in a court to support a similar request. MPs told the government six years ago that it "could not have done a better job of failing to represent the interests of British citizens".

At the time Liberal Democrat MP David Heath said, "We expect the British government to protect and preserve the interests of British citizens, just as we would expect the American government to do the same for their citizens."

That argument may appeal to President Obama. Today 40 MPs have sent him a letter pointing out the unfairness of the arrangements and highlighting McKinnon's Asperger's syndrome.

This law is a relic of the Bush-Blair madness. Surely it is time for Gordon Brown and Alan Johnson to forgo the need for this rather humiliating appeal and step in to help McKinnon.