IN June 1999, Donna Tinker stabbed and killed her husband, Richard. As she ironed her children's clothes in the kitchen of their Harrogate home, he put his arm around her throat and pressed the hot iron to her face. At just five feet tall and weighing eight stones, the mother-of-three knew it was useless to struggle against her 16-stone husband. Panicking, she grabbed the first thing to hand - a vegetable knife - and struck out blindly behind her. The single blow punctured Richard's lung and he died in hospital a week later.

It was not the first time Richard had been violent towards Donna and, at first, she denied stabbing him, unaware how ill he was and terrified he would recover and punish her. This made the police doubt her story and later went against her in court. Despite evidence of violence, including a black eye, broken tooth and bruised jaw sustained just an hour before the stabbing, her defence of provocation was rejected. This ruled out a conviction for the lesser crime of manslaughter. Donna was found guilty of murder in April 2000 and sentenced to life in prison.

"Donna Tinker's case is typical of the way women are dealt with by the justice system," says Sue Griffiths of Justice for Women, a feminist organisation that campaigns for women who kill their violent partners.

"Women are far more likely to be killed than to kill but they are treated very harshly. Men receive far more sympathetic treatment and more lenient sentences."

She cites the case of Leslie Humes, a 40-year-old solicitor from Rotherham, who was jailed for seven years at Sheffield Crown Court in July after pleading guilty to manslaughter by reason of provocation. His 36-year-old wife, Madeleine, told him she did not love him and had feelings for another man. He stabbed her 12 times, in front of their four children, and she later died in hospital.

"It seems to be generally accepted that a man can be provoked if his wife leaves him or is unfaithful but a woman cannot be, even if she has suffered years of domestic violence and abuse. It is grossly unfair and it completely fails to take into account the effects of domestic violence on a woman."

Justice for Women, which is based in Leeds, has campaigned on behalf of a number of women since it was set up in 1990. Several have had their murder convictions overturned, including Kiranjit Ahluwalia, from London. In 1989, after ten years of violence and sexual abuse, she set fire to her husband Deepak's bedclothes while he slept. The trial judge ruled that the violence she had suffered was not serious and she was sentenced to life imprisonment for murder.

An appeal was granted in 1992 on the grounds that expert evidence and pyschiatric reports had not been presented at the trial. A re-trial was ordered and, in September 1992, she was found guilty of manslaughter due to diminished responsibility and sentenced to three years and four months - the time she had already served.

Donna Tinker is hoping for a similar result. Justice for Women took up her case and found her a new legal team, headed by Redcar MP and barrister Vera Baird QC. Earlier this week, three judges in London heard the 32-year-old's appeal against conviction.

Donna only told the police about the stabbing after her husband's life support machine had been turned off, and the jury was told she had made up the story about being threatened once she realised she had killed him.

But, during the two-day appeal hearing, the judges heard new video testimony from Natalie, Donna's nine-year-old daughter, who now lives with her two sisters with their maternal grandparents near Newcastle. She confirmed Donna's story, saying she had seen "Richard put the iron in mummy's face". Evidence has also come to light from a neighbour who gave a statement to police on the day of the stabbing and said they had seen a broken iron on the kitchen floor.

The judges are due to announce their ruling today. If the appeal is successful, Donna and her supporters are hoping for a re-trial and a manslaughter conviction, which could see her walk free.

Sue says: "We can help people but the real tragedy is that we can only help those who come to our attention. We have had several successful appeals but it is not enough. The system itself needs to be changed.

"In a lot of cases, the legal representation women get lacks the expertise to represent them and their experiences of domestic violence. The CPS must go back and look at these cases in greater detail. They must start understanding what happens within a relationship where domestic violence is involved and they must stop punishing women even further by charging them with murder."

Justice for Women has made some progress. In 1992, the organisation was approached by Emma Humphreys, from Nottingham. A prostitute from the age of 16, she was offered a home by client, Trevor Armitage, who became increasingly possessive, subjecting her to extreme physical, emotional and sexual abuse. On one occasion, terrified he would rape her again, she slashed her own wrists and stabbed him. She was convicted of murder and spent ten years in jail before winning an appeal on the grounds of "cumulative provocation".

"This was a big step forward because it recognises that provocation doesn't have to be just one occasion and that it can happen over a period of time - months or even years. Unfortunately, it has been inconsistently applied and we then had the case of Diana Butler, from Doncaster, who was convicted of murder, although her partner had been violent and sexually abusive to her for over two years. She won her appeal but she shouldn't have been charged with murder."

Earlier this week, the Attorney General Lord Goldsmith called for longer sentences for men who kill their partners. He is currently dealing with three cases, including that of Leslie Humes, in which appeals have been lodged against the leniency of the sentence.

David Perry, counsel for the Attorney General, told the Court of Appeal that over the past decade a sentence of up to seven years had become "almost the norm no matter how exceptional the case or great the culpability of the offender".

He said the current level of sentencing did not reflect what a "civilised society" should have regard to when dealing with someone whose partial defence to taking life was: "my partner was going to leave me and I couldn't face that".

Sue welcomes the move but wants more done to redress the balance. She says: "This just deals with one aspect of the problem. It addresses the lenient way men are treated but it does nothing to help women who are charged with murder after sometimes years of violence. The message is still going out that it okay to control your wife but it is not okay for a wife to be angry and fight back. I simply cannot understand it."