A 1998 Otago University study shows that women are more likely than men to be the perpetrators of physical abuse of their partners, while a 1999 Auckland University study shows that men and women are at least equally responsible for assaults.

The Otago University Multidisciplinary Health and Development Study, which has followed 1037 people from birth through to their early 20s, created a political storm in the United States where it was published.

It shows that about 27 per cent of women and 34 per cent of men reported they had been physically abused by their partner. About 37 per cent of women and 22 per cent of men said they had perpetrated the violence.

However, the violence perpetrated by men was more likely to result in criminal action, as it was more likely to be severe enough to injure the victim.

The commission has set a deadline of this month for submissions on its discussion paper Battered Defendants: Victims of Domestic Violence Who Offend.

The report says the law is sometimes unable to deal with battered defendants, and proposes options such as lesser sentences for retaliatory murder, and a defence of "diminished responsibility". It deals in depth with the battered woman syndrome, but has been criticised for failing to deal with battered men.

Mana Men's Rights Group, in a submission, argues that it is difficult for men to defend themselves against allegations of abusing their partners, and even harder when they are also a victim.

Spokesman Bruce Cheriton said there were only four protection orders against women in Wellington region and more than 8000 against men. Men were treated more harshly by the courts if they hit their partners, he said. A battered man who killed his wife "would be doing life".

Auckland Men's Centre adviser Jim Bagnall said he knew of a case in which a battered man had called the police 97 times before they did anything. "By that stage he needed 36 stitches in his head, and his partner got only 18 months in jail."

Separated Fathers Support Trust spokesman Warren Heap said his organisation had tried unsuccessfully to set up a men's refuge in Auckland, because he believed battered men were committing suicide rather than complaining to police.

But Women's Refuge head Merepeka Raukawa-Tait said the evidence she had seen indicated that women were much more likely than men to be the victims of domestic violence. She also said: "I do believe there is an increase in violence, by women, toward their partners. It's just following the general trend of an increase in violence in our society."