Geoffrey Robertson: An immoral and unlawful decision

To send McKinnon to the US is in breach of his most fundamental rights as British citizen

The Home Secretary has decided he is powerless to stop the extradition of Gary McKinnon to Virginia, where he will be denied bail and sentenced to at least 10 years' imprisonment for an offence that would not deserve custodial sentence in Britain and notwithstanding the fact that he has Asperger's and is very likely to commit suicide.

This decision is morally wrong because his case cries out for compassion. It is also mistaken in law, because the Government has overlooked the most fundamental right of a British citizen, guaranteed by the 1689 Bill of Rights, not to be subjected to any punishment which is "cruel and unusual".

Alan Johnson, like the courts, has merely decided that punishment in the US will not be contrary to the European Convention bar on "inhuman and degrading" treatment. That may well be so: Americans are not inhuman and imprisonment in Virginia may be no more degrading than imprisonment here. But our constitutional prohibition on punishment that is "cruel and unusual" raises a different question.

It became part of our law at the time of the Glorious Revolution because of public outrage at the inappropriate penalties on a clergyman, Titus Oates, who was whipped and pilloried and defrocked for perjury. Today, it stands as a protection for citizens against sanctions which are inappropriate or over severe by British standards or which may cause an individual exceptional mental anguish – in short, against punishments which do not fit the crime. And by that yardstick, a10-year sentence in a foreign jail imposed on a near-suicidal man, who would if prosecuted here in all probability receive a non-custodial sentence – is about as cruel and unusual as it gets.

What, after all, was McKinnon's crime? From an upstairs flat with an ancient laptop he hacked into US army computers with a gusto and brilliance inspired by his undiagnosed compulsive disorder, causing damage (more than he realised) estimated at about £400,000. It has been said that he was looking for UFOs, but that is to diminish him. He left a very clear political message on the computers he accessed: "US foreign policy is akin to government sponsored terrorism these days."

Jejune and mistaken, no doubt, but remember "these days", back in 2002, were days when US foreign policy had gone beyond bombing al-Qa'ida in its caves and had invaded Afghanistan, putting suspects in boiler suits and flying them to Guantanamo Bay. McKinnon was making a political protest, and once handcuffed to US marshals should be considered for "prisoner of conscience" status by Amnesty International.

McKinnon's political protest was a crime nonetheless, which caused damage. It was committed in this country as well as in the United States and he should be judged and sentenced in either place in the same way that other political protesters are sentenced here when they cause damage by disrupting US bases or nuclear facilities or Greenpeace targets. We try to convict them (sympathetic juries sometimes acquit) and we usually give them suspended sentences to deter them in the future or possibly short custodial sentences. Even the famous "Committee of 100" protesters, which closed a US airbase at Wethersfield at the height of the Cold War, received only a two-year sentence, and that was condemned as too severe by the whole Labour movement at the time.

Some years ago I defended a young man whose hacking was alleged to be even more serious that McKinnon's. He was the "datastream cowboy" who hacked into US army computers and was said by the prosecution "to have caused more damage to the Pentagon than the KGB". He was tried here and received a non-custodial sentence.

So by our standards, and through our eyes, a 10-year sentence (it may be more – he faces charges carrying up to 60 years) on Gary McKinnon would be wholly disproportionate especially since the crime was committed almost eight years ago and driven by an undiagnosed disorder over which he could have no control.

It is obviously cruel to extradite a man in his condition without ensuring that he will be entitled to bail – another Bill of Rights guarantee, incidentally, which the Home Office irresponsibly ignored when agreeing his extradition conditions with the US. The suffering he will undergo in serving a lengthy prison sentence, exacerbated by his condition, will be exceptional enough to reach the cruelty threshold, and the uncontradicted psychiatric evidence is that it will amount to a death sentence.

Why has the Bill of Rights never been mentioned in the McKinnon case? It has never been referred to in or by the courts, in the parliamentary debates or, I suspect, in the legal advice to the Home Secretary. Have we lost all memory of our own hard-won historic liberties – liberties that were watered down in 1951 for a European Convention on human rights that had to be couched in lowest common denominator language? MPs can still get excited about the breaches of their own rights guaranteed by this 1689 Act, when police raid Damian Green's office or a Trafigura injunction threatens to stop parliamentary reporting.

If they care about their own liberties, they should care about the liberties of others that were guaranteed by the same constitutional settlement. If the Home Office legal advisers imagine that the European Convention has repealed or overridden the 1689 Act then they are blatantly mistaken: Article 53 of the Convention itself expressly preserves our existing liberties – won in this case in what we like to call our "Glorious Revolution".

Alan Johnson, when he recently appeared before the Home Affairs Committee, showed a somewhat unnecessary resentment at the pop stars and pop papers that have taken up McKinnon's cause. He told the Committee, "I feel strongly that these issues should be dealt with on the basis of justice."

So they should, but he does not seem to have been advised that justice in this country, as Portia explained in The Merchant of Venice, comes seasoned with mercy. That imperative of kindness is in our law as in our literature: it is the badge of this nation's commitment to humanity and it empowers the Home Secretary to halt this extradition.

Geoffrey Robertson QC is the author of The Tyrannicide Brief