Legal experts are calling on the government to remove legislation that allows Child, Youth and Family to place young offenders into police custody once they've appeared before a court.
Yesterday RNZ revealed the number of nights youth offenders spent in police cells had nearly tripled in a single year, with 151 nights spent in police custody in 2015-16 - up from 51 in 2014-15.
Young people aged between 14 and 16 can be remanded in police custody if Child, Youth and Family cannot provide a bed for them at a youth justice residence. It is meant to be a last resort option.
Children's Commissioner Judge Andrew Becroft said it was time to abolish this practice, once and for all.
"We've seen an erosion of good, community-based facilities - everyone in the system knows that.
"Let's be blunt: the time has come just to grasp the nettle, remove the [police custody] option once and for all, and to say to Child, Youth and Family services, it now is 'use our community-based resources'".
There should be only short-term use, of up to 24 hours, when young people are transferred around the country, he said. "It can be done."
Making this happen would require an amendment to a section of the Children, Young Persons and Their Families Act, which gives CYF the power to pass teen offenders on to police if they cannot find suitable accommodation.
CYF will become the Ministry for Vulnerable Children in April, and Judge Becroft said this change gave an opportunity to make inroads.
Dean of Otago University's law school and family law specialist Mark Henaghan said there was no good reason not to change the legislation.
"The whole purpose of the Children, Young Persons, and their Families Act - far reaching and very wise legislation - is to keep young people who may get involved in activities which we would term criminal, out of the criminal justice system.
"The minute you start putting them in police cells, you've already put them in the system."
Mr Henaghan said the new ministry should look at other options for housing offenders, even if it came at a greater cost.
"This would be a superb investment, to invest in secure places, where young people - if they do have to be held, for whatever reason - a secure place to hold them, which is humane and dignified and not a prison cell, with hardened adult criminals right next door to them or possibly even in the same cells."
Labour Party child welfare spokesperson Jacinda Ardern said housing teens in police cells had no place in a civilised society.
"Young people are treated differently in our youth justice system, and for good reason: there's an expectation we will have the potential for a successful intervention for these kids.
"The first step to that is keeping them away from the adult justice system. Now if from day one you're putting them in police cells, then you're really depleting your ability to do that."
In a statement, the Ministry of Social Development - which runs CYF - said it was always exploring alternatives to police cells.
"Keeping young people out of police cells is not just a matter of making more youth justice beds available.
"It's about having an effective range of options available and finding the right placement for each young person, which might be in the community or might be in a youth justice residence. A residence is only one option."
While it refrained from directly addressing the question of legislation change, CYF said there would be reforms on the horizon, with the raising of the youth offender age to 17 to take effect in 2019.
"The timing of the change allows for a wider set of reforms, including the overhaul of care and protection, to be fully implemented first.
"The overhaul of care and protection reforms will be implemented from 2017 and are aimed at reducing demand for youth justice residence beds and free up capacity for 17 year-olds to be included in the youth justice system," said the statement.