Last Sunday, David Miranda was detained while changing planes at London Heathrow Airport by British authorities for nine hours under a controversial British law -- the maximum time allowable without making an arrest. There has been much made of the fact that he's the partner of Glenn Greenwald, the Guardian reporter whom Edward Snowden trusted with many of his NSA documents and the most prolific reporter of the surveillance abuses disclosed in those documents. There's less discussion of what I feel was the real reason for Miranda's detention. He was ferrying documents between Greenwald and Laura Poitras, a filmmaker and his co-reporter on Snowden and his information. These document were on several USB memory sticks he had with him. He had already carried documents from Greenwald in Rio de Janeiro to Poitras in Berlin, and was on his way back with different documents when he was detained.
The memory sticks were encrypted, of course, and Miranda did not know the key. This didn't stop the British authorities from repeatedly asking for the key, and from confiscating the memory sticks along with his other electronics.
The incident prompted a major outcry in the U.K. The U.K.'s Terrorist Act has always been controversial, and this clear misuse -- it was intended to give authorities the right to detain and question suspected terrorists -- is prompting new calls for its review. Certainly the U.K. police will be more reluctant to misuse the law again in this manner.
I have to admit this story has me puzzled. Why would the British do something like this? What did they hope to gain, and why did they think it worth the cost? And -- of course -- were the British acting on their own under the Official Secrets Act, or were they acting on behalf of the United States? (My initial assumption was that they were acting on behalf of the U.S., but after the bizarre story of the British GCHQ demanding the destruction of Guardian computers last month, I'm not sure anymore.)
We do know the British were waiting for Miranda. It's reasonable to assume they knew his itinerary, and had good reason to suspect that he was ferrying documents back and forth between Greenwald and Poitras. These documents could be source documents provided by Snowden, new documents that the two were working on either separately or together, or both. That being said, it's inconceivable that the memory sticks would contain the only copies of these documents. Poitras retained copies of everything she gave Miranda. So the British authorities couldn't possibly destroy the documents; the best they could hope for is that they would be able to read them.
Is it truly possible that the NSA doesn't already know what Snowden has? They claim they don't, but after Snowden's name became public, the NSA would have conducted the mother of all audits. It would try to figure out what computer systems Snowden had access to, and therefore what documents he could have accessed. Hopefully, the audit information would give more detail, such as which documents he downloaded. I have a hard time believing that its internal auditing systems would be so bad that it wouldn't be able to discover this.
So if the NSA knows what Snowden has, or what he could have, then the most it could learn from the USB sticks is what Greenwald and Poitras are currently working on, or thinking about working on. But presumably the things the two of them are working on are the things they're going to publish next. Did the intelligence agencies really do all this simply for a few weeks' heads-up on what was coming? Given how ham-handedly the NSA has handled PR as each document was exposed, it seems implausible that it wanted advance knowledge so it could work on a response. It's been two months since the first Snowden revelation, and it still doesn't have a decent PR story.