Joanna Blythman on torture

If, like me, you're hooked on BBC One's spy drama Spooks, you'll know that the last series ended on a stomach-churning cliffhanger with two of our heroic MI5 intelligence officers, Adam and Jo, captured by a group called Red-backs that specialises in torturing spies to extract intelligence.

The Red-backs' Torquemada polishes his suitcase full of state-of-the-art information-extracting kit while a tape of the agonising screams of their fellow officer, Zaf, being tortured to death is played into their cell to soften them up before their interrogation. So deeply does Jo dread what lies ahead - "They'll use electricity", she says - that she begs Adam to kill her rather than face the pain.

Does he or doesn't he? We won't know until the next series, and it doesn't matter anyway, since Spooks is fictional and quite possibly misleading. If the case of terror suspect Binyam Mohamed is anything to go by, rather than being on the receiving end of torture, MI5 is more likely to be participating in it, if not directly, at least by proxy.

The details that emerged at the High Court in London last week of MI5's complicity in torture would not be out of place in an illegal video nasty and should shame any civilised country. The court heard how Mohamed, an Ethiopian asylum-seeker who was given leave to remain in London while his case was resolved, was arrested for a visa violation in Pakistan, denied a lawyer, and after being interrogated by an MI5 agent there, secretly rendered to Morocco on a CIA plane.

Mohamed cannot speak for himself - he is the only British resident being held at Guantanamo Bay, and so represented by lawyers from the legal rights group, Reprieve - but claims that his Moroccan captors tortured him, stripping him naked and cutting him with a scalpel on his chest and penis. After 18 months of this he was transferred to what is known as the "Dark Prison", near Kabul, Afghanistan, a secret prison run by the CIA.

Mohamed's description makes the blood run cold: "It was pitch black, no lights on in the rooms for most of the time They hung me up for two days. My legs had swollen. My wrists and hands had gone numb. At one point, I was chained to the rails for a fortnight The CIA worked on people, including me, day and night. Plenty lost their minds. I could hear people knocking their heads against the walls and the doors, screaming their heads off."

But what is MI5's role in all this? The Home Office insists our security and intelligence agencies don't "participate in, encourage or condone the use of torture". For his part, Mohamed says that his interrogators asked him questions about his life in London which could only have been provided by the British intelligence services.

And in their ruling last week, Lord Justice Thomas and Mr Justice Lloyd Jones seemed more persuaded by Mohamed's version of events, concluding that MI5's role was "far beyond that of a bystander or witness to the alleged wrongdoing".

Does it bother you if potential innocents become casualties in "the war on terror"? It does me. The law lords should not have to remind the UK and US governments that "the torturer has become like the pirate and the slave trader before him an enemy of all mankind".

Whether it's rendition flights from Prestwick or sickening mediaeval sadism in Kabul, colluding with the US's blunderbuss "anything goes" abuse of anyone it imagines might possibly be involved in terrorism is not only morally repugnant, but also cowardly.

Confessions extracted under torture are notoriously unreliable. I dare say that if someone was about to take a hacksaw to my knees I'd say anything that they wanted to hear. But this should never be mistaken for reliable information.

In the case of Guantanamo Bay detainees like Mohamed, "confessions" gleaned from prolonged torture form the tenuous basis of the grave charges against them.

In his particular case, the law lords have told foreign secretary David Miliband to share evidence (of extraordinary rendition and torture) that would help prove Mohamed's innocence, giving him one week to consider the attendant security implications.

In the absence of such evidence, Mohamed will appear before a US military commission - previously described by Lord Steyn, another British law lord, as a "kangaroo court" - where he will be tried solely on the basis of these dubiously obtained admissions.

If found guilty, he faces the death penalty.

David Miliband has a chance to do the right thing here, to break the pattern of Tony Blair's supine compliance with US human and civil rights abuses. He could go further and set up a new code for our security services that bars them from facilitating torture.

It's obvious that our law lords mean to stand up to the government on the rights of terror suspects. Ex-Guantanamo detainees are bringing claims for damages, and demanding a public inquiry into British government and security service collusion in the human rights abuses they have suffered. So why keep defending the indefensible?