Shami Chakrabarti, Liberty director
Civil rights campaigner Shami Chakrabarti has announced her resignation from Liberty Getty

Shami Chakrabarti is the civil rights campaigner who did not let personal attacks get in the way of her quest to make the UK a fairer place. The Liberty director may have been mocked as "Shami, Shami, Shami" by radio presenter Jon Gaunt, and described as "the most dangerous woman in Britain" in the commentator's Sun column, but that did not stop the 46-year-old from defending the outspoken host when Talksport sacked him.

Gaunt, who had been in care himself, accused a Redbridge councillor of being a "health Nazi" after the local authority proposed banning smokers from fostering children. Chakrabarti argued her former critic should not have been dismissed and wrote to Talksport.

"As someone who has been on the receiving end of Jon Gaunt's blunt polemic in print and on the radio, I believe that the airwaves of a great democracy would be the poorer for his absence. I urge you to reinstate Mr Gaunt's programme without delay and have offered him support in the unlikely and unfortunate event that recourse to the Human Rights Act proves necessary," she said.

Gaunt was never reinstated by Talksport but he now sings the praises of his unlikely defender on his new station, Talk2MeRadio. Gaunt's was just one of the many cases Liberty and Chakrabarti have taken on since she joined the human rights group in 2001 from the Home Office as an in-house lawyer, later becoming Liberty's director in 2003.

The role has seen the second-generation immigrant (Chakrabarti was born to Hindu-Bengali parents in 1969) become a household name. She is a regular on current affairs shows such as the BBC's flagship debate programme Question Time and was named in a 2010 Telegraph feature as one of Britain's most powerful women. When the Olympics came to London in 2012, Chakrabarti was chosen as one of the flag carriers.

But beyond the TV screens, the civil liberties activists was conducting some important work, even when her causes were not fashionable. Probably one of her most well-known campaigns was against New Labour's attempts to introduce identity (ID) cards.

In a pre-WikiLeaks and Ed Snowden age, the then home secretary David Blunkett argued that the scheme would help the authorities crackdown on crime and illegal immigrants.

But Chakrabarti, a graduate of the London School of Economics, warned the proposed programme would only increase discrimination. "The emphasis on immigration as the justification for an ID card is of itself, we say, going to increase the likelihood of discrimination in the application of the card, and also, crucially, in its two-tier staged nature it is in itself discriminatory," she told the Home Affairs Committee in 2004.

"We have had advice that it may well breach the new law in targeting initially foreign nationals, including EU nationals, for the bite of the scheme before it becomes compulsory later down the line for British nationals."

However, the scheme was watered down and eventually scrapped when the coalition government came into power after the 2010 general election.

But Chakrabarti's notoriety has been accompanied by criticism, notably in The Spectator magazine. Former BBC Radio 4 Today programme editor Rod Liddle has accused her of having "more job titles than an African dictator", while Douglas Murray described Liberty's pro-Human Rights Act video as a "misinformation campaign".

However, even her detractors, including Liddle, admit Chakrabarti has had a highly effective campaigner at Liberty; she will stay at the organisation until her successor is found. Frances Butler, Liberty's chairwoman, said: "Under Shami's transformative leadership, Liberty has greatly extended its expertise, influence and membership."