People should not be held in custody while waiting for bail documents, the IPCA says.
The Independent Police Conduct Authority says people shouldn't be detained while awaiting bail documentation at courts, after a woman was left unattended in the cells for almost six hours.
The IPCA has released a report into the incident which makes a number of recommendations.
It wants the police commissioner to review the People in Police Detention policy, and says people shouldn't be held in police detention when waiting for bail documents.
"People should await the bail documentation in a bail room rather than be taken into police custody," the IPCA report reads.
When that isn't possible, the report says the required steps set out in the current policy regarding police detention should be amended to "reflect the practicalities of the court environment".
The report was led by Judge Colin Doherty, the chair of the Authority.
The incident in question happened in December 2017 at the New Plymouth District Court.
A woman was taken into police custody while waiting for court staff to complete her bail documentation, but when court adjourned for the day the woman was left unattended for almost six hours.
The report found officers did not follow proper procedure, which led to the woman being left in the cells.
"This happened as a result of human error. The officer involved acknowledged the mistake and police sent a written apology to the woman," Taranaki Area Commander Inspector Keith Borrell says.
"While the officer's actions were accidental, an employment investigation was undertaken in relation to her actions. This incident should not have occurred and changes have been made as a result."
The police accepted the findings of the report. In a statement, the police say they have conducted a review of their policy and made changes to ensure people awaiting bail documentation are in a suitable waiting area, rather than court cells.