After serving 10 years and three months in prison for killing her violent, drunken partner, Emma Humphreys walked free from the Court of Appeal - cleared of murder, and advancing the legal rights of battered women.

Pale, nervous and very thin, she was engulfed by dozens of cheering women and childrenoutside the courts.

Now campaigners will turn their attention to the cases of 70 other women serving jail sentences for killing brutal partners or husbands - including Sara Thornton, whose case first put domestic violence on the political and law reform agenda.

Yesterday, led by the campaign group, Justice for Women, they immediately called on the Home Secretary to review each case in the light of the appeal court ruling which quashed her murder conviction and substituted a verdict of manslaughter on the grounds of provocation.

Lawyers said the judgment strengthened and clarified the defence of provocation on behalf of victims of domestic violence driven to kill. It spelt out for the first time that not only must trial judges detail any history of abuse, they must also analyse and explain its significance to the jury.

Further, it underscored an earlier Court of Appeal ruling that personality traits - such as "battered wives' syndrome" - and any effects on behaviour, should be taken into account when considering provocation.

Rohit Sanghvi, Miss Hum-phreys' solicitor said: "This is a landmark decision. It means that in future, if there is a doubt, judges must leave cases of abuse and battered women to the common sense of the jury."

The three appeal judges had been told Miss Humphreys, now 27, had led a tragic life of family breakdown, care and institutions. She had started drinking and taking drugs, running away from home and had slit her wrists many times.

In a letter to the judges written from prison, she said she was 12 and at school when she first cut her wrists. "Someone took a little notice and at last I wasn't sent back home. I was 12 and running from hell." At 16 she turned to prostitution.

A year later, in 1985, she was found guilty of stabbing to death Trevor Armitage, a drug addict twice her age who had picked her up off the streets and subjected her to months of beatings, rapes and verbal abuse. He had previous convictions for violence and, said the appeal judges, "a predilection for girls much younger than himself".

But despite his violence and his demands that she continue to work as a prostitute, he had been the only person in her life to tell her he loved her - adding to her confused life.

On the night she killed him, they had come in from a pub where he had been drinking with his son and some male friends. On the way home, he had promised them a "gang bang", causing her grave distress. She went upstairs armed with two knives and slashed her wrists.

Armitage's reaction when he found her was to undress in anticipation of having sex and taunt her about the "pathetic attempt" to cut her wrists. She plunged the knife into his chest, penetrating his heart.

Lord Justice Hirst said that on the night in question there was the cumulative provocation of the drunkenness, the threatened "gang bang", his nakedness posing an unwanted threat of sex and, finally, the "wounding taunt" about her cut wrists - providing the final trigger which caused Humphreys' self-control to snap.

Lord Justice Hirst said the trial judge had failed properly to direct the jury on the cumulative effect on Humphreys of these. Instead he had only given "a mere historical recital, devoid of analysis or guidance, and that was not sufficient".

Sitting with Mr Justice Kay and Mr Justice Cazalet, he concluded that the trial judge had also given a "fundamentally flawed" direction when he told the jury to ignore evidence of Humphreys' "abnormal personality" - a trait which had developed out of her "miserable" history. This included immaturity and the attention-seeking habit of cutting her wrists. "It was clearly open to the jury to conclude that the provocative taunt (which led to the killing) inevitably hit directly at this very abnormality, and was calculated to strike a very raw nerve, " he said.

At a press conference after the hearing, Miss Humphreys vowed to fight for further changes in the law, alongside the women who campaigned for her. In the meantime, she is to receive counselling and help to her rebuild her life.