Along with others, he recently contributed to a book on the type of domestic violence committed in Hong Kong and how it can be alleviated. Titled Preventing Family Violence - A Multidisciplinary Approach (Hong Kong University Press), it includes cases of violence against elderly relatives, children, spouses and other partners.

For years, Chan concentrated primarily on spousal abuse, but having two children of his own made him also reflect on the disturbing prospect of violence committed against youngsters. In more than one-third of families in which violence occurs, there is child abuse along with spousal abuse, he says.

Factors such as the economy can contribute to abuse. Fallout from the 2008 economic crisis continues to reverberate in some families, Chan says.

'The cycle is such that the impact on the family lasts even when the economy improves,' he says. 'During economic difficulties, stress in the family is quite high and there is more conflict. Even when the economic situation becomes stable, the conflict is not resolved ... Even when they earn more money, it's not that easy to resolve it.'

Although Hong Kong is a modern city, many women have traditional views of the partner's role - one that may be difficult to live up to, Chan says. These women may expect their partners to be the protectors, the main wage earners and so on, and stress builds when reality fails to match expectations, which can sometimes lead to violence.

But whether the violence stems from external factors or the psychological make-up of the abuser, Chan argues that any assault should result in mandatory arrest, adding that even if a man hits his partner only once, he needs to be stopped before the violence escalates. The problem in Hong Kong, however, is that while the government has strengthened the ordinance dealing with domestic violence, only a smattering of cases actually end up in court.

Chan estimates more than 80 per cent of cases never go to court; the abuser sometimes is simply bound over by police.

'It's useless. You're saying: 'Next time we'll take it seriously and arrest you',' he says.

The problem is not that Hong Kong lacks the law to enhance protection, Chan says. It is non-enforcement of the laws that do exist.

Police often vacillate on whether to arrest an abuser in a domestic violence case, generally preferring to refer it to the Social Welfare Department as a private matter, but Chan is critical of this approach.

Rather than repeatedly ask the victim whether the abuser should be arrested, Chan argues that a trip to court should be mandatory as is the case in some states in the US.

'The police's role is not to judge whether it is a criminal case,' he says. 'Their role is to collect evidence and then leave it to the court to decide whether [the person is] guilty and on the level of punishment. By just referring the matter to the social welfare system to be handled by social workers, it is not giving full recognition to cases to provide legal support.

'So the message sent to the offender is worse. It seems to the abuser that even the police don't feel it is sufficiently serious to follow up,' Chan says, adding that many abusers also refuse to attend appointments with their assigned social workers.

For lesser cases of violence, he suggests that abusers could be required to join a group in the batterers intervention programme, where they would receive counselling to help them change rather than rely on their conscience. Only about 10 per cent of abusers want to change their behaviour, he says.

Because the programme is voluntary in Hong Kong, Chan calls for abusers found guilty in lesser cases to be given the option of joining instead of a jail sentence. If the abuser has completed the programme to the satisfaction of his social worker, the threat of prison is lifted.

'I believe [abusers] can change. I have counselled batterers in group and individual settings, and, in my experience, group work can be more effective,' he says.

Chan cites positive results when his team invited a former abuser to join their sessions and share his experience in reforming his behaviour and mindset.

Intervention group members learn from one another: 'While they relate their experience of using violence, they are not accepting this behaviour,' Chan says. 'But at least they can accept one another's stress and difficulties.'