Liberty is always a rollercoaster ride and last week was more so than most. As an organisation dedicated to protecting civil liberties we began defending the free speech of Sun journalist and former Talksport radio presenter Jon Gaunt. He once thought me “the most dangerous woman in Britain”, but Britain it seems, is even more dangerous now. Hired to be a colourful “shock jock”, he was then summarily terminated for calling a local councillor a “Nazi” and a “health Nazi” in a heated debate about the wisdom of banning smokers from fostering children. Is passionate argument and rudeness to be censored? Are there to be no warnings or second chances in post-Brand/Ross radio?

Then the horrific atrocity in the land of my forefathers; the sub-continent that my small son has yet to visit but like thousands of other young Britons feels so much kinship with. This civil libertarian needs no reminding of the enormous burden of policing open societies in the face of the bloodthirsty.

So imagine my surprise when the call came about the dramatic police operation against Damian Green MP on suspicion of “aiding and abetting” a Home Office leaker. Surely the anti-terror cops have enough on their plate without responsibilities for internal Whitehall discipline? Surely the threat posed by mild-mannered parliamentarians doesn’t require the heavy mob? Perhaps pots might better investigate kettles than the Yard inquire into civil service leaks.

It is always dangerous to speculate about ongoing investigations, but Liberty was founded in response to overzealous antidemocratic policing, and questions must be asked.

As a former Home Office civil servant and lawyer, I well understand the importance of confidentiality. Any organisation that feels undermined by an employee is entitled to investigate suspected breaches of trust. I would even concede that in the sensitive environment of that department, it may be necessary to call in the police to establish the identity of a suspected mole and the extent of potential lapses. But why, particularly in the apparent absence of threats to national security, is it so often necessary to rush to criminal justice rather than discipline or even dismissal?

Then to Green himself. The legal creativity of investigating an elected politician for presenting leaked information to the public is obviously dangerous enough. Given the constitutional sensitivities, why arrest him rather than offer the opportunity to attend for interview by arrangement? This was after all considered adequate for Tony Blair in the small matter of cash and peerages.

Just as Sir Ian Blair is leaving the Yard in a cloud of bluster about political interference with policing, the bruised and battered Met now faces the inevitable charge of interfering in the political process. Who made this judgment in the public interest? When does irony descend into farce?

If I ever was the most dangerous woman, I suppose I must concede the potential dangerousness of the MP for Ashford. But a danger worthy of nine hours’ detention and up to nine counter-terror officers raiding his home does seem a bit of a stretch.

Then there is the small question of the integrity of parliament. Who exactly in the house authorised the raid on a member’s office, and while we’re about it, why the execution of this whole operation at a time when parliament has risen for a few days and difficult questions are harder to ask?

Who first briefed the press that Green had been arrested? Was this itself an unethical leak? Why were some senior politicians rather than others informed of the operation in advance? Given that the whole saga began with a Home Office complaint, did no one in the ministry of the interior know about the parliamentary side of the investigation?

These and so many other troubling questions may remain unanswered for some time, maybe until the conclusion of initial investigations. But of course that timetable conveniently rests with the police. Further, the Independent Police Complaints Commission has proved a less than fearsome watchdog to date. It seems to make too many friends and does not always bark in the night. Perhaps it might surprise me this time.

More happily, the much-maligned Human Rights Act struck a blow for press freedom in the context of another recipient of leaked information, the local journalist Sally Murrer. The case against her, built on bugged conversations with her police officer source, collapsed under the weight of her right to free expression which necessarily requires the protection of journalistic sources.

I have neither a borrower nor a leaker been and have often criticised “off-the-record briefings” relating to policing and security matters. However, it is one thing to establish ethics and discipline in an organisation and quite another to punish politicians and journalists whose free speech is essential to democracy, and whose job it is to disseminate information in the public interest.

The events of last week demonstrates the extraordinarily tough challenges faced by the new acting Metropolitan police commissioner Sir Paul Stephenson. I wish him so very well in the task of bringing calm, judicious policing to the capital. I may even send him a nutcracker this Christmas. He has inherited too many sledgehammers.

Shami Chakrabarti is director of Liberty

Times Recommends

• Tear down this wall! And save the planet
• Double click if you want the bin emptied
• Have you got permission to read this?