In going to the Court of Appeal over the Binyam Mohamed case, MI6 was not trying to protect information that may have come out about his mistreatment in either Pakistan or Morocco. It was trying to protect the "control principle" that any intelligence material is shared with a partner country only on the condition that it is kept secret there as well.
The principle is at the heart of real intelligence co-operation between countries. More sharing of information is a constant rallying cry of terrorism analysts. In truth, little information of any value is actually shared unless it operates under a tight control principle.
So yesterday's judgment in the Court of Appeal upholds the control principle but still releases the offending seven paragraphs on the basis that they are already in the public domain in the US. The legal nicety of that will not play particularly well with Washington's security services. There may be a clear civil rights interest in releasing this information but in the US the fact is that secret material it shared with the British has now become a source of public embarrassment – for the second time.
How much damage will it do to the rather special intelligence relationship between Washington and London? Some, certainly. It is hardly the biggest security breach that has occurred between the two partners and they have powerful joint interests to keep on sharing high-quality intelligence.
Nevertheless, the fall-out will have to be managed. President Obama may have dropped the "war on terror" label but there is still a big difference of mindset between a US approach that goes out to get the terrorists, and a British approach which treats terrorists as criminals and relies on the rule of law. The criminal justice approach is often hard to reconcile with the protection of intelligence. The Government's continuing tussle with the judiciary over the use of control orders is a symptom of the problem.
Ultimately, the security services will know that Washington has done worse to us. In summer 2006 the Bush administration was given top-level access to British intelligence on the plot to blow up a number of airliners over the Atlantic. Without consultation, it moved to foil it in Pakistan and forced the British to spring their arrests early when the evidence was still partly circumstantial. It took three years and two separate trials before the evidence that the British security services regarded as conclusive convinced the juries. That caused a bit of fall-out too.
Professor Michael Clarke is the director of the Royal United Services InstituteReuse content