A male rape victim who kills his attacker after being taunted over what happened could avoid a murder conviction under reforms outlined yesterday. Similarly, a mother who returns home to find a man raping her daughter and kills the assailant could also be sentenced for manslaughter rather than murder.

Both could use a proposed partial defence to murder – that they were motivated in response to words and conduct that caused them to have a “justifiable sense of being seriously wronged”. The defence should be used only in exceptional circumstances, a government consultation paper said. The reforms would make clear that a partner having an affair would not come into this category.

A spokesman for the Ministry of Justice said: “The idea that this will be used by people to get off the hook when they kill a neighbour in a dispute or someone in the street when they get into a row is quite wrong.”

The proposals are part of reforms that amount to the biggest overhaul of murder laws for half a century. The partial defence of provocation would be scrapped, as would the term itself, which the Ministry said had negative connotations.

A second proposed partial defence would help spouses or partners who kill in response to a fear of serious violence. This is aimed at a victim of sustained abuse who kills his or her abuser to thwart an attack that is expected, but may not be imminent.

Alternatively, the killer might have overreacted to what he or she perceived as an imminent threat, the paper says. The reforms would scrap the present need for the killer to have suffered a “sudden” loss of control.

The reforms draw on recommendations from the Law Commission, the Government’s law reform body, which said in 2005 that murder laws were a mess. They noted that, while appeal judges often did in practice free battered women who killed abusive partners, this was not available as a defence in the first place.

Maria Eagle, the Justice Minister, said that, under the proposed changes, more partners – mostly men – would be convicted of murder. “This area is one of the most important where the law is out of kilter with modern needs,” she said. “For men and women who kill their partners, these changes will mean that the letter of the law finally catches up with judges and juries who, in recent years, have been less prone than people think to let men off lightly and punish women harshly.

She said that there were no immediate plans to look at degrees of murder as proposed by the Law Commission nor was there to be a review of the mandatory life sentence for murder.

A series of cases has highlighted the defects in the law. In 1997 Joseph Swin-burne was sentenced to 200 hours’ community service after he stabbed his wife 11 times when she told him that she was leaving him for another man. The case of Kiranjit Ahluwalia was one of several in which woman fought against murder convictions after killing abusive husbands. She was jailed for life for killing her violent husband in 1989 by setting his feet on fire after years of abuse, but was freed on appeal three years later. Her story was made into a film.

In 1995 Emma Humphreys succeeded in overturning a conviction for murdering her boyfriend when aged 17, ten years earlier. She died three years later of an accidental drug overdose.

Vera Baird, QC, the Solicitor-Gener-al, who has acted for many battered women, said: “The days of sexual jealousy as a defence are over. In cases like Emma Humphreys’, the Court of Appeal extended the defence of provocation as far as it would stretch.”

She added that the new partial defence of killing from losing self-control from fear of serious violence would provide a tailored defence to cases such as this.

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