The windswept edges of the Thames on a cold Sunday afternoon earlier this month were a far cry from the comfortable Government offices that Shami Chakrabarti left three years ago to join the civil rights group Liberty.
She was outside the walls of high-security Belmarsh Prison to lead a protest, which has pushed her onto the national stage and into direct conflict with the Government over the detention without trial of nine foreign nationals who are suspected of terrorist activities.
The following day, Chakrabarti led the Liberty team in the House of Lords appeal against the legality of the detention of the nine suspects under the Anti-Terrorism, Crime and Security Act, passed after the 11 September attacks. The decision could take some time to emerge.
Taking on a Labour government like this doesn't come naturally to Liberty - several current MPs used to work there. Secretary of State for Trade and Industry Patricia Hewitt was general-secretary of the group in the 1980s, and Home Office Minister Fiona Mactaggart was chair. The solicitor-general, Harriet Harman, was legal officer there.
But Chakrabarti is clear where she stands. "To its credit, the Government introduced the Human Rights Act 1998 and has done a lot of good work on anti-gay and sex discrimination," she says.
"But it has been very authoritarian in its approach to social policy, looking for maximum sanctions and wider police powers." she said. She added that in relation to asylum, New Labour has continued down a road first trodden some years earlier by the Conservatives: "These policies contribute to a complete dehumanisation of asylum seekers in this country, which can't just be blamed on the tabloid press."
Chakrabarti was a barrister practising in public and common law before joining the Home Office as a legal adviser in 1996. During the five and a half years she spent there, she developed a firm understanding of the mechanics of Parliament, working on the passage of 12 bills and becoming one of the Home Office officials responsible for the implementation of the Human Rights Act.
Despite being a harsh critic of the Government's social policy, battling on many fronts including asylum, ID cards and anti-terror laws, Chakrabarti has good memories of her time at the Home Office. "It was a real privilege to advise ministers on legislation, and my work there was fascinating, but I am not the sort of person to spend my whole career in one place," she says. "Some people crave job security, but I much prefer an element of uncertainty."
Liberty was founded as the National Council for Civil Liberties in 1934.
It is made up of a charitable trust that provides legal advice, education and research into human rights, an association run by members and a company that employs staff.
Chakrabarti feels that the public aspect of her role as director of a civil rights group gives her more chance of winning the current legal challenge in the House of Lords than if she was an anonymous civil servant.
"This is a campaign that has been primarily focused on the courts and Parliament, and ultimately it is very clear that we won't resolve the situation without winning some public support," she says.
Two years ago, the Special Immigration Appeals Commission, which has access to secret intelligence used to arrest terror suspects under the Anti-Terrorism Act, concluded that allowing people to be detained indefinitely is unlawful and a violation of basic human rights. But the Court of Appeal went against the commission's decision and supported the Home Secretary's view that foreign nationals, who are the main targets of anti-terror laws, do not have the same rights as British citizens.
To avoid becoming entangled in the twists and turns of legal procedure, Chakrabarti turned the campaign's focus away from complex legal issues, and towards the moral and political arena: "At the protest you would not have heard a single piece of legislation mentioned - just simple, plain English about why this is wrong, as opposed to unlawful. That is the argument that has to be made, in addition to legal action."
She deliberately works outside her comfort zone by not conducting any litigation herself. Instead she leaves that to Liberty's team of lawyers while she works hard to get to grips with areas that are not part of her previous experience, such as financial and strategic issues. "A lot of lawyers are a bit anti-management," she says. "It is very easy to be snooty about management because you see yourself as a clever professional doing something very demanding and intellectually stimulating, and that management is a lot of spin."
But for Chakrabarti, management has a very concrete human purpose because it affects the daily working life of her staff. "It is all very well to say that Liberty protects civil rights, but this does not mean anything unless we are also committed to treating our staff well," she says. "People here work very hard for very little money."
Although exposing the Government to public embarrassment can be a risky business, Chakrabarti can count on the support of her trustees, who are also full members of the organisation. "I have really supportive trustees because we are clear about what our values are," she says.
"I do not relish criticising the Government for the sake of it. I am not a revolutionary - just look at my background. But in times of legitimate fear of terrorism, one has to be quite vocal in the protection of civil liberties."