The latest reporting on the Snowden docs by The Guardian shows that the UK's surveillance operation GCHQ was apparently well aware that its activities were almost certainly open to a "legal challenge" and therefore they were committed to keeping them secret to avoid such a challenge
. Note that this is quite different than the official excuse always given about being worried about public disclosure putting national security at risk by revealing "sources and methods." Instead, here it seems clear that the secrecy was for the very reason that many of us suspected: they were pretty sure they're breaking the law, or at least coming so close that it was something the courts would eventually have to decide... but only if the info got out. And, it wasn't just them. They realized that the telcos willingness in passing on info likely opened up other legal challenges as well.
GCHQ lobbied furiously to keep secret the fact that telecoms firms had gone "well beyond" what they were legally required to do to help intelligence agencies' mass interception of communications, both in the UK and overseas.
GCHQ feared a legal challenge under the right to privacy in the Human Rights Act if evidence of its surveillance methods became admissible in court.
GCHQ assisted the Home Office in lining up sympathetic people to help with "press handling", including the Liberal Democrat peer and former intelligence services commissioner Lord Carlile, who this week criticised the Guardian for its coverage of mass surveillance by GCHQ and America's National Security Agency.
Amazingly, they seem to admit that the fear of a public debate/legal challenge was the key reason
they fought (and won) a battle to keep such evidence out of trials. That is, even though they could have gone with the old favorite of "national security," instead, they finally admitted reality:
Our main concern is that references to agency practices (ie the scale of interception and deletion) could lead to damaging public debate which might lead to legal challenges against the current regime.
That other point mentioned above, about telcos going "above and beyond" in voluntarily handing over access is also pretty big, considering that the telcos in question had tried the "we're just complying with the law" excuse in the past. But, evidently, they were lying.
The revelations of voluntary co-operation with some telecoms companies appear to contrast markedly with statements made by large telecoms firms in the wake of the first Tempora stories. They stressed that they were simply complying with the law of the countries in which they operated.
In reality, numerous telecoms companies were doing much more than that, as disclosed in a secret document prepared in 2009 by a joint working group of GCHQ, MI5 and MI6.
Later in the report, a GCHQ memo notes that telcos "feared damage to their brands" if the extent of their over-cooperation was revealed. You know how they could have dealt with that? By not going so far above and beyond the law. But, once again, it seems like the telcos have been incredibly willing to screw over their own customers' privacy at every opportunity.