Kafkaesque rendition

Lawyers acting for Binyam Mohamed, a British resident incarcerated in Guantánamo Bay, are asking the high court to order the government to disclose information that, they say, would show the evidence against him was obtained by torture.

The government is fighting the case. Of course, it does not want to reveal what Britain's security and intelligence agencies knew about the US secretly transporting "enemy combatants" to places where they were likely to be tortured, the practice known as extraordinary rendition. To bolster its case, it has used its last resort, hoisting the flag of "national security". We have seen it before, most recently over the decision to stop the Serious Fraud Office inquiry into allegations of bribery in the sale of warplanes to Saudi Arabia, and we will no doubt hear it again.

In this case, the government has told the high court that Britain is "hugely dependent in a number of areas on US intelligence". That intelligence relationship, it says, is grounded in the "fundamental principle" that no information passed between the two countries will be disclosed to a third party without the consent of the country that provided the information in the first place.

"Any disclosure, however limited, would seriously undermine this principle to the point that future cooperation between the UK and its most valuable intelligence partner, the US, would be severely jeopardised," the government argues. "This would pose a very serious risk to UK national security."

Kafka would have been delighted. The government says that Britain's national security depends on the intelligence the US gives us in what it appears to admit is an entirely one-sided relationship. Actually, it goes further. It implies that only by being subservient to the US can Britain defend its national security. So what is meant by our "national security"? The interests of our security and intelligence agencies? They are in a uniquely privileged position. They have sight of information that may save lives if it is used to thwart a terrorist attack. They also, as in the Mohamed case, have access to information that could save a man's life and help to put a stop to torture.

The government's argument is that to protect our "national security", we need to kowtow to the US. It is in this context that we should consider government statements, notably by the foreign secretary, David Miliband, about US assurances over rendering suspects through UK territory. Twice the government has had to correct assurances given to parliament. Now Time magazine reports that, despite repeated denials by Washington, an (anonymous) former senior US official has said that the US imprisoned and interrogated one or more suspects on Diego Garcia, the main island of the British Indian Ocean Territory.

The high court has heard that the US refused to tell British officials that Mohamed - whom they accuse of supporting and conspiring to commit acts of terrorism by flirting with an alleged "dirty bomb" plot - had been secretly rendered to Morocco rather than being sent from Pakistan to Afghanistan, as MI5 and MI6 were told. The US refused to say where Mohamed was, yet MI5 repeatedly supplied information for US officials to use in Mohamed's interrogation. The US then supplied Britain with the "fruits" of that interrogation. Or, rather, a few pickings. British security and intelligence officials did not press the US to tell them where Mohamed was being held. In such a lopsided relationship, it may not be surprising.

Lord Justice Thomas, who heard the case, and plans to give his ruling later this month, said it raised some "very troublesome issues". It certainly does.

Richard Norton-Taylor, he Guardian's security affairs editor.