A string of murders of dissidents had bathed the streets of Tehran in blood. Shirin Ebadi, a lawyer and human rights activist, recalls with a shiver the day she read in an interior ministry file that she was next on the regime’s hit list.

“I remember mostly an overwhelming feeling of disbelief,” she said. “Why do they hate me so much?”

She went home, took a long shower, and only after dinner, when her two daughters had gone to bed, did she tell her husband: “So, something interesting happened to me at work today.”

It is hard to picture this tiny middle-aged woman, barely 5ft tall, as the scourge of the mullahs in Tehran. But she has become their worst nightmare. Imprisoned, harassed and interrogated, this 59-year-old lawyer and mother of two has become the champion of Iran’s most vulnerable citizens. Her clients are abused children, battered wives and, more dangerously, its political prisoners.

Awarded the Nobel peace prize in 2003 Ebadi is a reluctant heroine. “Ever since I received this prize I’ve been trying to fight against this idea,” she said. “Creating heroes is a very dangerous thing.”

On a rainy afternoon in Paris, promoting her memoir Iran Awakening, she seems exhausted, worn out from the tension of habitual fear: “If you want the truth, yes, frankly I am afraid,” she said. “Fear is an instinct like hunger. It comes to you whether you want it or not.”

But whatever her reservations about the government in Tehran, she is just as uncompromising a critic of America. American military action to put pressure on Iran to relinquish its nuclear programme would be disastrous, she says, and Iranians would defend their land from invaders “to the last drop of blood”. The military option “endangers nearly all of the efforts that democracy-minded Iranians have made in these recent years.

“The threat of military force gives the system a pretext to crack down on its legitimate opposition and undermines the civil society that is slowly taking shape.”

Looking back, the most galling thing for Ebadi, perhaps, is the role she played in bringing the mullahs to power. “Who did I have more in common with? An opposition led by mullahs who spoke in the tones familiar to ordinary Iranians or the gilded court of the shah, whose officials cavorted with American starlets at parties soaked in French champagne?” she said.

She attended the rallies, she joined hundreds of thousands of people each evening in crying “Allahu akbar” (God is greatest) from the rooftops and rejoiced when the shah, carrying a canister of Iranian soil, departed for Egypt.

She believed in the dawn of an era of justice. “I felt that I too had won alongside this victorious revolution. It took scarcely a month for me to realise that, in fact, I had willingly and enthusiastically participated in my own demise. I was a woman, and this revolution’s victory demanded my defeat.”

The purges and oppression soon began. She was dismissed from her post as a judge and for years suffered the indignity of serving as a clerk in the very court she had once presided over.

Unlike so many others, however, she decided to stay and fight the system from the inside, a decision for which she has often been criticised. “I’m an Iranian,” she likes to say. “I am staying.”

When the new draconian legal code was published in a newspaper Ebadi read it in astonishment. “They had gone back to the 7th century for their legal advice.” From that moment she understood her best weapon against the regime would be her deep knowledge of the law. Her goal was to beat the mullahs at their own game. She immersed herself in “musty books of Islamic jurisprudence”, looking for sources that stressed the “egalitarian ethics of Islam” instead of the patriarchal version favoured by the ruling clergy.

In 1992 she was finally granted a licence to practise as a lawyer and found herself grappling with the inherent contradictions of Iranian society: a ferocious theocracy whose legitimacy was nonetheless based on civil law.

Born into a well-to-do family, Ebadi, her two sisters and brother were brought up as intellectuals and taught the value of education.

This obsession goes some way towards explaining why she has not completely turned her back on the revolution. When it comes to inheritance a woman’s claim is worth half that of her brother, yet today 65% of Iran’s university students are girls compared with only 25% in the days of the shah. There is only one word, she says, to describe Iran under the mullahs: paradoxical.

At the remarkably young age of 22, when miniskirts were all the rage in Tehran, Ebadi became the country’s first female judge. Her girlfriends idolised Twiggy and other western fashion icons, but Ebadi was not interested.

“Law books and ideas interested me more than interior design. My career struck fear in the hearts of Iranian men. The moment they thought of marrying me, they imagined themselves in a marital tiff with a judge – supposing, I assume, they could not just say ‘because I said so’ and slam a door.”

In the end she married Javad, an electrical engineer, though she points out that he, like all Iranian husbands, expected his wife to find time in her busy legal schedule to shop, clean and cook and raise their children.

In 2000 the mullahs lost patience with this troublesome housewife. She was accused of “propaganda against the Islamic republic” and put in prison. Behind the walls of Evin, a prison in Tehran, she knew that the law would not apply. “They could lash my bare feet with electric cables until I confessed my crime,” she said. She spent several weeks in solitary confinement before being released.

Although shaken by this episode, she did not give in. When the government, cowed by the growing unrest of its citizens, took the extraordinary step of acknowledging the existence of death squads in the interior ministry, Ebadi saw her chance. She applied for interior ministry files relating to a series of murders by these death squads.

She read with horror the accounts of writers, academics and poets murdered in their homes for having incurred the wrath of the state. Then a chilling sentence jumped off the page: “The next person to be killed is Shirin Ebadi.”

Last week she returned to Tehran, where her book will not be published. What drives her back, when she could live like so many of her compatriots a life without fear in London or Paris? Her answer is disarmingly simple: “Iran is my country.”