The Snowden revelations in the Guardian showed the most catastrophic secret accretion of power by the British state in our peacetime history, yet the reaction on this island that invented liberty under the law has been beyond parody. The three lines of defence of our freedoms – the press, parliament and the law – have so far bent the knee to the secret state.

Newspapers that are meant to defend freedom have argued instead for the investigation of the Guardian, while the House of Commons has proved itself an overblown electoral college from which the executive is selected, rather than an independent legislature with clout to hold ministers to account.

GCHQ has the capacity to scoop up and store the email and voice traffic of the entire population of this country, regardless of whether they are suspects or have ever committed any crime. GCHQ says it only looks at the suspect messages, but what are its checks? Given its inability to keep its own secrets, how credibly can it promise to keep ours?

The invasion of privacy is breath-taking. The defence that you have nothing to fear if you have nothing to hide is as outrageous as it was when made by the totalitarian states. Citizens may – for good or bad reasons – want their activity to be private without in any way being illegal. Privacy matters.

Not only were the cabinet and National Security Council not told of this programme, neither was the committee set up to scrutinise the communications data bill (proposed by the Home Office to take the same police powers that GCHQ already exercised). We know of the Home Office's disingenuous deception from a pair of former chief whips – the Tories' David Maclean (now Lord Blencathra) and Labour's Nick Brown. These are not lightweight players, and they were shocked.

Where were the watchdogs? After huffing and puffing about how everything was in order, the Commons intelligence and security committee has at last announced an inquiry. We can write its conclusions. It will give GCHQ a clean bill of health, and argue for some modest improvements in controls.

How do I know? Look at the composition of the committee, which is hand-picked by the prime minister, and only rubber-stamped by the Commons. All its MPs are paid-up members of the security establishment. Sir Malcolm Rifkind is chair, even though he had executive responsibility for the agency he is now overseeing when he was foreign secretary.

The home affairs select committee under chairman Keith Vaz has succumbed to pressure from rightwing Tory MPs to investigate not the disastrous state invasion of privacy, but the behaviour of the Guardian in bringing it to our attention. And the joint committee on human rights – which includes peers as well as MPs – has stayed bizarrely silent even though state aggrandisement at the expense of individual freedom falls squarely in its remit.

Surely the first question is who signed off this programme? I discount the possibility that GCHQ went rogue. Its head at the time, Sir David Pepper, was a bureaucratic stickler. Sir David Omand, cabinet office permanent secretary in charge of intelligence, would also have insisted on ministerial sign-off.

So which prime minister and foreign secretary were responsible? Given that the Home Office later thought a full-scale parliamentary act was necessary to take similar powers for the police – the communications data bill – just what was the legal basis of GCHQ's activity?

The GCHQ Tempora programme was trialled in 2008. The decision might have been taken as early as 2006, which would put it just within the purview as foreign secretary of Jack Straw (June 2001 to May 2006). It is more likely to have been Margaret Beckett (May 2006 to June 2007) or David Miliband (June 2007 to May 2010).

If it was David Miliband, this may well explain why the Labour frontbench has been so muted. Though Ed Miliband has been happy to admit past Labour errors on Murdoch and other matters, his appetite for political fratricide may be sated.

And the responsible prime minister? Tony Blair resigned in June 2007, so either he or Gordon Brown could be responsible. Was the Labour cabinet told? Or was this an extraordinary instance of prime ministerial authority and our "elective dictatorship"? These questions are of constitutional importance, but none of them has been asked, let alone answered.

If parliament is condemned to behave like the executive's poodle, we will have to rely on the law. Liberty is taking a case to the Investigatory Powers Tribunal, but GCHQ has boasted to its US counterpart that it has never lost a case before that body, and that its compliance regime is substantially more lax than the Americans'.

That leaves judicial review. As Lord Macdonald QC, the former director of public prosecutions, says: "The question is whether the government had proper lawful authority for what they have done. It is potentially a subject for judicial review." There is an overwhelming democratic interest in testing whether that decision was ultra vires – outside legal powers voted by parliament.

There is normally a three-month time limit with judicial review, but that should not be an impediment when the powers continue to be used and when the original decision was secret. The Snowden revelations show an executive arm snatching exaggerated powers with no public debate or parliamentary approval. For the sake of our freedoms, but also our democracy, this needs to be put right.