Women who kill their male abusers are often failed by a British justice system that can treat them as cold-blooded murderers rather than seeing them as victims too, campaigners said on Wednesday.

Changes to criminal and legal systems are needed to ensure fairness for women who frequently serve long prison sentences for killing violent or controlling partners, the Centre for Women’s Justice and Justice for Women said in a joint report.

The report reveals “a real lack of understanding and insight into domestic violence” in Britain, said Harriet Wistrich, the director of Centre for Women’s Justice.

“If somebody kills because their life is under threat or they have been horrendously abused over many years … that is not the same as someone who coldly plans to kill somebody to benefit,” she told the Thomson Reuters Foundation.

“They have acted out of desperation and they are deserving of leniency at the very least.”

The Ministry of Justice did not immediately respond to a request for comment.

“We recognise the devastating impact of domestic abuse on victims,” said a spokesman for the Crown Prosecution Service (CPS), which prosecutes criminal cases in England and Wales.

“Prosecutors take all relevant factors into account when deciding the appropriate charge,” said the spokesman.

Nearly 40% of female homicide victims were killed by a current or former partner, against just 4% of male victims, according to the Office for National Statistics.

When women do kill their partners it often follows abuse, said the report, subtitled: “How the state criminalises women we might otherwise be burying”.

A review of 92 women who killed men found evidence of previous violence or abuse by the men in more than three-quarters of the cases it studied over a decade.

Forty of the women were convicted of murder, with a similar number found guilty of manslaughter.

Only six were acquitted, the report said.

Both the law and how it is applied stymie justice, it said.

Researchers found examples of the CPS pursuing murder charges inappropriately and refusing plea bargains from women, the report said.

Myths about how a victim of abuse ‘should’ behave were found to influence many cases and were believed not just by jurors, but also by advocates and judges, researchers said.

“If women don’t fit the stereotype of a victim this can be a problem,” said one lawyer interviewed for the report. “X was loud, she was a Scouser, she answered back, she wasn’t the typical victim and that didn’t work well for her in court.”

Defence lawyers, too, often lack the skills or time to fully investigate and depict any abuse pre-murder, it found, while women were more likely to use a weapon than men, which is treated as an aggravating factor in sentencing.

The report called for better training about domestic abuse in the justice system, reforms to court processes to support women giving evidence and changes to sentencing guidelines.

“All of these women are victims first and foremost,” said Vera Baird, the Victims’ Commissioner, at a virtual launch.

She backed calls for a change in the law, giving women the right to respond with greater force to abuse, similar to a provision for householders reacting to intruders at home.

“There is more leeway for me to protect my house then there is for me to protect my body against an attacker,” she said.