Indigenous people facing criminal charges in NSW are more likely to have bail denied by police.
A study by the NSW Bureau of Crime Statistics and Research analysed more than 500,000 bail decisions made by the state's two bail authorities - the police and the courts.
The analysis found legal factors - prior offending, the seriousness of the offence and so on - were the primary factor in determining bail.
However, when compared with non-Indigenous defendants in similar positions, police were more likely to reject bail if the offender was Indigenous.
Some 4200 adults were in prison on remand awaiting legal proceedings last December, more than a quarter of them Indigenous.
Among juvenile offenders on remand, Indigenous people made up almost half.
Given the over-representation of Indigenous people in custody, the findings warrant further investigation, BOCSAR executive director Jackie Fitzgerald said.
"It remains possible that Aboriginal people are disadvantaged in police bail decisions and that this is contributing to their over-representation in custody," she said.
A new BOSCAR study would be undertaken to determine definitively whether the Indigenous bail result was due to bias.
The study also found inconsistencies were rife between different geographical areas.
Moving between different police jurisdictions or magistrates in some cases appeared to have a greater impact on the probability of bail refusal than many legal factors, including prior court appearances and bail breaches.