Whether or not you support the Snowden leaks, what has happened since is disquieting

Of course national security must be paramount. But there are lines to be drawn

Edward Snowden’s actions in themselves were tricky enough to judge, given the grey area where privacy and national security must be balanced. For some, the revelations of mass snooping by US – and by extension British – intelligence services were sufficiently egregious to merit the theft and exposure of classified National Security Agency files. For others, the disclosures merely confirmed that the spooks are doing their jobs and, unforgivably, revealed our hand to those that would harm us.

As the ripples from the NSA leak widen, the situation only becomes trickier. The latest twist is the detention at Heathrow of the partner of a journalist closely involved in publicising the affair. David Miranda’s travails provoked much outcry. In essence, however, the authorities’ interest in him is not so outlandish. Although not an employee of The Guardian, nor was Mr Miranda – as was first supposed – merely an uninvolved spouse. He was on his way home to Rio de Janeiro, via London, from a Berlin meeting with a filmmaker who has collaborated on the newspaper’s NSA-related coverage. His flights were paid for by his partner’s employer, and he was carrying memory sticks that contained information provided by Mr Snowden.

If one accepts the Government view that the leak endangers national security, then police interest in Mr Miranda and the “stolen” information in his possession is, at least, consistent. Indeed, it would be surprising – remiss, even – were all possible efforts not made to recover the material. So much for the principle. In practice, the response was grossly disproportionate.

Mr Miranda is not a terrorist, nor was he ever suspected of being one; the basis for his detention under anti-terrorism legislation is therefore flawed, despite police claims of narrow legality. Furthermore, while there is some dispute over whether the Brazilian was or was not given access to a lawyer, the simple fact of his being held for the full nine hours – seven of them with nothing to drink – smacks more of bullying than effective questioning. Demands for social-media passwords salted by threats of prison only compound the impression of wilful heavy-handedness.

Even more concerning, though, are the broader questions the incident raises. It was always difficult to believe that the decision to stop Mr Miranda was the sole preserve of the Metropolitan Police. Sure enough, the list of those who admit advance knowledge of the plan grows longer by the day. The Prime Minister, the Home Secretary and US intelligence were all in the know, it now transpires. Even though Mr Miranda was no mere partner, then, his detention was no routine police matter either. And if loutishness on behalf of our own security services would be bad enough, the slightest hint of British policing conducted by remote control from Washington is even worse.

Nor do the shenanigans stop there. We now know David Cameron and Nick Clegg put pressure on The Guardian – via Cabinet Secretary Jeremy Heywood, no less – to destroy the Snowden data in its possession. In a scene that would be hard to believe had it not actually happened, the stand-off ended with GCHQ officials overseeing the destruction of computers at the newspaper’s office. With so many copies of the information elsewhere in the world, the gesture is at best a token one. Yet the message was considered to be worth sending.

Of course national security must be paramount. But there are lines to be drawn – between the message and the medium, between Britain’s interests and America’s, between enforcement and intimidation.