Profile: Shami Chakrabarti

HER enemies – and she has a few – are revelling in the irony. Shami Chakrabarti, the ubiquitous elfin-faced champion of civil liberties, plans to sue a Government minister for comments he made about her relationship with senior Tory David Davis.

In an interview with Progress magazine, Culture Secretary Andy Burnham referred to "late-night, hand-wringing, heart-melting" phone calls between the two as Davis tried to make his mind up about resigning over the issue of the 42-day detention limit for terror suspects. Burnham had since apologised and said these were "light-hearted comments", but Chakrabarti, who is married with a six-year-old son, begged to differ. To her, they constituted a slur on herself and Davis, who is also married.

The following day, she accused Burnham of debasing "a great office of state" and threatened legal action if he failed to apologise for the "innuendo" – a move, however understandable given her circumstances, that may prove injudicious. The director of Liberty using the libel law to try to curtail freedom of speech? You can see how that will play in the Sun, whose columnist Jon Gaunt once branded Chakrabarti "the most dangerous woman in Britain".

It is a risky move from the former Home Office lawyer, who cites To Kill A Mockingbird's Atticus Finch and Martin Luther King among her heroes. Since she joined the civil liberties group the day before 9/11, 39-year-old Chakrabarti has won admirers from across the political spectrum with her passionate contributions to the debates on issues such as CCTV and identity cards.

Little known when she took over at the helm of Liberty, she quickly became a household name, appearing on programmes such as Question Time and The Moral Maze. In 2005, she was placed on a shortlist of 10 in a Today programme poll to find who really runs Britain, and the following year she came second to Jamie Oliver in a Channel 4 award for the Most Inspiring Political Figure.

The key to Chakrabarti's success is the fact she manages to act as a thorn in the side of New Labour, while maintaining an aura of unfailing middle-class respectability. Despite the strength of her convictions, she refuses to indulge in hectoring, rabble-rousing rhetoric, which might alienate listeners, speaking instead in a measured tone which lends credibility to her opinions.

As a CBE and member of the governors of the British Film Institute, she is firmly embedded in the establishment – a fact she reinforces in interviews, emphasising she is not anti-American or anti-police. And yet, by sticking up for the rights of suspected terrorists she cannot be seen as anything other than outside the political mainstream.

Chakrabarti's well-cut dark suits and kohl-lined eyes can make her look a bit severe and she herself worries she may come across as intense and miserable. Indeed, she often refers to herself as the grim reaper because "you know if you see me something awful has happened or is about to happen".

But even though discussions with Chakrabarti tend to plough territory not generally associated with belly-laughs, her self-deprecating sense of humour shines through. "I'm not a vegetarian, I just look like one," she once said.

She is not averse to engaging in a degree of populism to get her point across either. In an interview a few years ago, she turned her attention to the Harry Potter books. A JK Rowling fan, she had cited The Order Of The Phoenix as a book about human rights "with the Ministry of Magic trying to stitch up Harry without any real evidence". Now, however, she said she was forced to accept the young wizard was a war criminal (on the basis he tortures one of Lord Voldemort's followers in the last book). "I feel as if I've just shopped a friend," she added.

The result is that Chakrabarti attracts praise from such disparate quarters as the death penalty-supporting former Home Secretary Davis and indie band the Dastards, whose paean to her contained the lyrics:

"I turn on my TV:

The only one I want to see

Is Shami Chakrabarti."

Chakrabarti was born in London is 1969 to Indian-born parents. She was only 12 when her interest in human rights was awoken by her father, a 1960s immigrant from Calcutta. "We were watching the news during the hunt for the Yorkshire Ripper," she has said. "He said you can't possibly support the death penalty. I said I did. And he said you don't understand: there is no justice system in the world that will be 100% perfect and you have to imagine what it would be like to be the one person in a million who is wrongly convicted of this terrible murder. And nobody believes you and go to the scaffold. Something sparked in me that day."

Inspired, she studied law at the London School of Economics, but decided against practising. "After graduation, I was going to work as a trader in the city and pay my way through film school," she has said. "But there was a recession and my arithmetic was terrible."

Instead – after meeting her future husband Martyn Hopper, now a City lawyer, she got a funded pupilage at a chambers and then went to work for the Home Office. By the time she joined Liberty she was pregnant and her hormones were raging.

"All I could think was that my friends at the Home Office were going to be a target and about my husband who was working in Canary Wharf," she has said. "I thought: 'Is this the time to be getting into the civil liberties market?'"

In the end it proved to be an astute move, given that civil liberties have very much on the agenda ever since. In the last few years, rarely a day has gone by without Chakrabarti's opinion being sought on issues such as rendition flights, Guantanamo Bay and constraints on imams' freedom of expression.

And therein lies the rub for Chakrabarti. Having opposed the introduction of the offence of glorification of terrorism, and defended the rights of those responsible for publishing the Danish cartoons of the Prophet Mohammed, any threat to take legal action against Burnham may be perceived as at best an over-reaction and, at worst, rank hypocrisy.

On political websites, the backlash has already started, with even traditional supporters questioning whether she has allowed her personal feelings to cloud her judgment.

It is tempting to conclude that in rising to Burnham's bait Chakrabarti is taking herself a little too seriously. And that perhaps it's time her sense of humour made a reappearance.

You've been Googled

• "I think I was probably a fairly precious, insufferable brat." Chakrabarti on her childhood.

• Chakrabarti raised eyebrows when she appealed for sympathy for the police officers who shot dead Jean Charles de Menezes, the Brazilian electrician. Later she called for the resignation of Sir Ian Blair, the head of the Metropolitan Police.

• She is to replace Jon Snow as the new chancellor of Oxford Brookes University later this year.

• Chakrabarti says she decided who to back in the last election just half an hour before casting her vote.

• Her father was a bookkeeper and her mother ran a shop.

• "Three months' detention without charge is the very antithesis of justice. This new British internment (is] as damaging to fighting terrorism at home as to defending our reputation around the globe." Chakrabarti on early proposals to introduce a 90-day pre-charge detention limit for suspected terrorists.