The detention of Glenn Greenwald’s partner does not raise any issues over the use of current anti-terrorism legislation to target journalism. The law says:

A person commits an offence if—
(a) he collects or makes a record of information of a kind likely to be useful to a person committing or preparing an act of terrorism, or
(b) he possesses a document or record containing information of that kind.

and

An examining officer may examine goods…for the purpose of determining whether they have been used in the commission, preparation or instigation of acts of terrorism

So flu researchers and train spotters beware, in fact almost anyone doing anything a terrorist might find useful should be careful – and who knows what terrorists find useful? And even asking such a question, let alone researching it, might turn up information which said terrorists may indeed find useful.

Bad laws may well appear absurd, but they are laws nonetheless, and they can lead directly to jail. But the issue here is not law, or acting in solidarity with an embarrassed ally, but powers that are on the brink of destroying the ‘watchdog’ function of journalism, and a society where a legislature with the resources of the 19C attempts to oversee a secret executive with the powers of the 21C.

When it comes to Edward Snowden, the security services clearly feel that they, and not journalists or MPs, are in the best position to decide on what elements of his revelations constitute a threat.

Guardian editor Alan Rusbridger, who published them, was told by one intelligence officer overseeing the destruction of a secret-stuffed laptop: “You’ve had your debate. There’s no need to write any more.” The literary equivalent of “Nothing to see here. Please move along.”

Clearly the scope of the terrorist threat is perceived to be any evidential questioning of the security services’ relationships with other powers and agencies, or any factually-based challenge to the mechanisms through which they monitor and interfere with lives.

The clarity ends rather abruptly. The evidence and facts required to make such challenges are – by the very nature of the activity – secret and therefore must likely be obtained or held illegally.

To make matters muddier, the argument has to be conducted largely by proxy.

No one speaks directly for the security services, or if they leak on their behalf, their simple message is that the public – and the press – must trust them: that the oversight mechanisms which govern them are more than sufficient; the powers under which they operate barely adequate.

This is hardly a unique position. Many of us feel that we should have more freedom to act, fewer restrictions on our behaviour, more resources at our disposal. As Lord Leveson discovered, newspaper editors are no exception, especially when it comes to the freedom to humiliate and shame celebrities, politicians, and anyone foolhardy enough to enter the public line of fire.

By comparison, the security services might be considered models of restraint. And there are indeed real plots and real threats.

Yet the revelations that our phone calls, internet searches, emails and texts are digitally stored and sifted, and the potential for such information to be bought and sold (see Leveson above, although not just by journalists but by lawyers, insurers, and private individuals) is a cause for concern that silence, or simple faith, cannot meet.

Thoughtful, liberally-minded providers of digital surveillance services to governments acknowledge the problem. This is Alex Karp of Palantir*:

In the case of government agencies, he suggests an oversight body that reviews all surveillance – an institution that is purely theoretical at the moment. “Something like this will exist,” Karp insists. “Societies will build it, precisely because the alternative is letting terrorism happen or losing all our liberties.” Forbes

No one seems likely to build it soon. Or to suggest how to oversee such overseers. In the meantime, we are witnessing the end of anonymous whistleblowing on the secret affairs of the state. As Rusbridger wrote in the piece linked above: “it may not be long before it will be impossible for journalists to have confidential sources.” This will make official scrutiny more necessary, and the bar of conscience yet higher.

Let us not be under the illusion that whistleblowers are saints, and journalists their priestly confessors. But let us neither imagine that surveillance is a sword only wielded by the just, and secrecy their only shield.

Absent a public debate and we must trust that our new security structures contain no young digital Edgar Hoovers awaiting their moment, and that the most sinister results of surveillance are embarrassments at airports and not the Stasi-esque nightmare fictionalised in The Lives of Others. If history suggests anything, it is that we will only find out long after the event. Technology, meanwhile, is finding out ever more, ever faster.

*Palantir is a member of the Technology Pioneer community of my employer, the World Economic Forum.