The Ministry of Education intervened last month after an Auckland school told a woman who lived within its enrolment zone that she could not enrol her child unless she had a 12-month tenancy agreement.
The Ministry said all children in New Zealand had the right to be enrolled in a state school for which they were in-zone, regardless of the length of time on their family's tenancy agreement.
YouthLaw general manager Darryn Aitchison told RNZ the school's rule was unlawful.
He said YouthLaw received more inquiries about enrolments at the start of the school year, but few involved situations where schools were actually breaking the law.
"We're not getting a lot of schools that are using illegal processes; what they're using are probably overbearing processes in many cases. So they're requiring things like statutory declarations, quite a lot of evidence - power bills, water bills, phone bills - that sort of thing.
"They often do require tenancy agreements, but we're not seeing a lot that require them to be for the exact school year," he said.
Aitchison said the rules around in-zone enrolments were clear.
"If a school does run a zone, they must enrol students who live in-zone and while the law doesn't say what exactly that means to live in the school zone, the Ministry of Education says it's simply the usual place of residence.
"It doesn't say anything about it having to be a fixed-term tenancy, permanent tenancy, owner-occupier. Simply if you make that house your usual place of residence, then you can be enrolled."
Aitchison said schools had a lot of autonomy over their rules and it was difficult for a family to challenge a decision because they did not have many accessible legal avenues.
He said it was more than likely children had been denied entry to their local school because their families did not realise they could challenge what the school was telling them.
"That would definitely be happening. That's an issue that sits right across the justice sector. They don't identify their issues as being legal," he said.
"They are not the experts. They are told certain things by schools, people in authority and they believe it and they don't recognise that there may be a legal remedy available to them."
Aitchison said some schools' requirements for proof of residence within the school enrolment zone were excessive.
"Some of the schools have statements on their stat decs just notifying families that they're committing a crime against the Crimes Act if they make false statements so they're quite heavy-handed some of them. I think they're unnecessary.
"Providing power bills, tenancy agreements, water bills that show the people residing there and the supply going to the property is probably enough. And it's also quite an effort and quite a burden on families.
"It may seem a small burden but you might have to sit in a queue at a local CAB (Citizens' Advice Bureau) for an hour-and-a-half with other people."