Harriet Harman, Labour's deputy leader, may not strictly be in charge of Downing Street at the moment, but you can hardly say that she's lying low. She is fronting the Government's proposals to reform the law on murder - along with Vera Baird, the Solicitor-General, and Maria Eagle, the Justice Minister. Under one of the amendments now up for discussion, a man who kills his wife for infidelity will be convicted of murder, straight up.

No excuses about provocation or loss of control, thank you very much. As Ms Baird put it: “The days of sexual jealousy as a defence are over.”

So much for poor Othello's account of himself as “one not easily jealous, but, being wrought, perplex'd in the extreme”. The Moor would get short shrift from Ms Baird.

But at the same time as making it more likely that men who kill women will be put away for life, another proposal would make it less likely that women who kill men will be convicted of murder. If a woman does away with her spouse on the basis that he abused her for years, she would no longer have to prove that she acted on the spur of the moment. She can claim “fear of serious violence”.

Of course, the law doesn't go in for generalisations to the effect that men are likely to lose it when they find their wife in bed with another man or when she's nagged once too often, while women go in for slow-burn grudges, which they prudently don't give way to until their abusive husbands are drunk or asleep.

But ministers do see homicide in pink and blue. Ms Harman puts the case for reform thus: “The reality is that, although it is not a gendered defence, 86 per cent of domestic homicides are committed by men, and the victims are their female partners. “The infidelity clause... is overwhelmingly used by men.”

The trouble is that these changes give the impression that the law would regard one kind of domestic violence (by women) leniently while viewing another kind (by men) as beyond the pale. The fact that they are being fielded by a trio of feminists such as Mses Harman, Eagle and Baird doesn't help matters. This, you feel, is the feminist take on murder.

In response, Erin Pizzey, the founder of the original battered women's refuge, points out that if women are in fear of violence, they should get out of the house where it's happening rather than killing the man concerned.

It is not the only contentious proposal. There would be a “words and conduct” defence for others who kill, neighbours, say, in a long-running dispute, people subjected to intolerable racist abuse or parents who see someone molesting their child - or think that there is molestation. So if you believe yourself to be “seriously wronged” and kill in consequence, you may face a lighter charge.

Feminists have argued for years that victims of domestic violence should not be treated as common murderers. Sara Thornton, whose case was turned into a television documentary, stabbed her husband Malcolm when he was drunk on the basis that he was violently abusive. (He, being dead, was in no position to put his side of the matter.) Her conviction for murder was later commuted to manslaughter.

Then there was Kiranjit Ahluwalia, a Punjabi woman, whose conviction for killing her husband was overturned on appeal to manslaughter on the ground of diminished responsibility; her story was made into a movie, Provocation. She said that her husband had abused her for a decade and had once pressed a hot iron to her face. She doused the blanket over his feet with petrol while he slept and set fire to him; he died of his injuries six days later.

And then there was poor Emma Humphrey, whose case established that provocation to murder could be cumulative. She was 17 when she killed her boyfriend and pimp, Trevor Armitage. He had boasted to two friends that they would gang-rape Emma. She slashed her wrists. When he came to her, naked, he taunted her with her injuries. She killed him with a stab wound to the heart.

These cases have already changed the way that the law treats women victims of abuse when they kill. I had the utmost sympathy with Emma Humphrey; I have rather less for Sara Thornton.

But that's the point. These are individual cases - they should be judged on their individual merits. And that means, I'm afraid, doing away with the mandatory tariff and giving judges discretion over sentencing. They may be risibly out of touch with how normal people see things, but they can distinguish between a man who smothers his terminally ill wife from someone who kills his neighbour in a rage about his leylandii from another who kills his children to get revenge on his cheating wife.

In return, it would be nice if judges had to take account of public sentiment in passing sentence and treat murder as seriously as most of us think it deserves to be treated - which is more than you can say for these politically motivated proposals.

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