The school had basic uniform and appearance requirements, he said. "It's about trying to keep it as simple as possible, like minimal jewellery."
Girls should have their hair tied back and for boys it should be off the collar, he said.
"It's about safety when working in workshops and labs and maintaining a neat appearance."
Dane Robertson, president of the Western Bay of Plenty Principals' Association, said he was unsure at this stage how the ruling would affect local schools.
He knew there were some schools in Tauranga that had rules around uniform and tidy appearances, including some that required boys' hair to be above the collar, similar to rules that asked girls to have no more than one piercing in each ear.
"There's a lot of questions raised about what this could mean for schools."
In his decision released yesterday, Justice Collins said the decision by St John's College to suspend Lucan was unlawful and the condition imposed by the school's disciplinary committee that he could return after getting a haircut was unreasonable.
The principal, Paul Melloy, needed to ensure serious disciplinary consequences were reserved for "truly serious cases", Justice Collins said.
"Mr Melloy did not appreciate the need to explore disciplinary sanctions less drastic than suspension in this case.
"The degree of seriousness of Lucan's continued disobedience was not great enough to warrant suspension."
Penalties imposed should minimise the disruption to a student's attendance at school, which was a factor that was overlooked by Mr Melloy, Justice Collins said.
Suspension was a last resort to be used if the student's behaviour was a harmful or dangerous example to other students, he said.
Justice Collins ordered St John's School Board to pay Lucan's costs.
In a statement, St John's College said: "Naturally we are disappointed in the decision made in Wellington today. The board of trustees is taking time to consider the judgment made by Justice Collins in terms of its impact, both on our school and on other schools." additional reporting APNZ