Libertarians and hawks will disagree about what intelligence agencies should be licensed to do, but both should surely agree that they shouldn’t break the law. A court ruled on Friday, however, that, in its dealings with the NSA, GCHQ had done that.

The court in question, the Investigatory Powers Tribunal, is so secretive that it doesn’t publish its address. During the hearings, officials refused to answer direct questions about the bulk interception programmes, sheltering behind a wall of bluster about hypothetical programmes whose existence they could neither confirm nor deny. Everything about the case confirms the British security state’s continuing failure to step out of the shadowlands created by the Official Secrets Act of 1911. This is so, even though the legal breach, a failure to publish safeguards to protect Britons’ privacy in the context of transatlantic intelligence sharing, might appear to be technical and narrow.

The missing safeguards were eventually extracted, it appears, after the IPT applied pressure in private, in the run-up to a December ruling that gave Cheltenham a green light to continue keeping electronic tabs on countless blameless citizens. The one legal question left hanging then was how it could have been lawful for GCHQ to have failed to produce these protections, at any point since the NSA’s Prism programme began, back in 2007. On Friday came the inevitable ruling that it was not.

The agency immediately dismissed its shortcoming as of merely “historic” interest. The Home Office flannelled about its “commitment to transparency”, while taking the chance to bury two controversial consultations under news of the adverse ruling. One covers the interception, including of legally, medically or journalistically privileged materials; the other, “interference with electronic equipment”, or in plain parlance, computer hacking.

None of the official lines dealt convincingly with the real issue: why the necessary safeguards were not produced. GCHQ was, presumably, reluctant to explain the rules that governed intelligence swapping, because it remains instinctively averse to admitting to any shared snooping at all – despite everything Edward Snowden revealed and the Americans now admit. The potential for a trade between NSA and GCHQ, where each spied on the other’s compatriots, to subvert their own legal protections, was always apparent to suspicious minds. Nothing in the ruling will have discouraged them.

Without the Snowden revelations, Friday’s case could never have been brought, and so GCHQ would still be operating unlawfully. Nobody who wishes intelligence to respect any sort of rules could want that, which surely means that everybody should be grateful to Snowden. But the agencies still don’t get it. No wonder they are getting frustrated by their lack of progress in persuading global tech giants to lend them a hand. For such cooperation will have to rest on consent, which is going to be hard to get for as long as there is an instinctive refusal to give anybody any idea about the rules to which they are working.