It found traditional gender norms which promote male dominance, aggression, strength, and violence-supportive attitudes were reflected in the OMCG lifestyle and were "well established as key determinants of violence against women".

"The strong group identity within OMCGs may reinforce and encourage these attitudes and norms," the researchers found.

"As well as leading to the objectification of women by OMCG members during club gatherings, these attitudes and norms potentially influence OMCG members' behaviour with women outside of these settings, including in their intimate relationships.

"The reputation of OMCGs for their culture of secrecy and intimidation of victims and witnesses also presents challenges in holding OMCG members accountable for domestic violence offending."

The researchers also found there to be "unique circumstances associated with OMCG-related domestic violence".

"Partners who seek help from police about domestic violence can be at increased risk of retaliation, not only because of the domestic violence report but because they may be perceived to be acting as an informant," the researchers found.

"This can make it difficult for victim-survivors to provide evidence."

This was reflected in the study's average 66 per cent guilty rate for OMCG members for their first finalised matter involving at least one domestic violence offence, compared with 80.7 per cent for non-OMCG members.

It also found OMCG members were more than twice as likely as other offenders to have had at least one domestic violence offence.

The research set out to develop a better understanding of the nature of domestic violence among gang members so police and specialist domestic violence units can "help identify the support needs of victim-survivors".

The research dataset looked at 3542 gang members and their "associates" drawn from the NSW police database and compared them with recorded criminal and custodial histories of a sample of 12,001 other non-gang affiliated offenders and studied involvement in domestic violence for a 10-year observation period.

"Given the small sample of OMCG members with a domestic violence offence, we used a statistical technique called 'nearest neighbour matching' to account for observable differences between the two groups," the researchers said.

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However, they also acknowledged there were "obvious limitations to relying upon recorded criminal histories to measure domestic violence offending, given the relatively low rates of reporting to police".

It found overall, two-in-five OMCG members (40.1 per cent) had been proceeded against for at least one domestic violence offence in the previous 10 years.

Even among the four largest gangs - those with more than 200 members - the prevalence of domestic violence offending ranged from 32.3 per cent of members to 44.1 per cent of members. The median harm to the victim-survivors associated with each finalised domestic violence matter also was significantly higher for OMCG members.

The rate of offending, they found, also varied between gangs.

The research concluded using recorded crime data "undoubtedly underestimates the true extent of OMCG-related domestic violence".

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