Cracks in the institution of school rules have begun to show.
St John's College principal Paul Melloy responded to the news saying he was "disappointed" at the ruling.
Other principals went further, one accusing Lucan's parents of backing their "belly-aching teenager".
Many thought it should never have gone to court.
The decision highlights the reality that disgruntled parents are now having more say over school operations, and the prospect of schoolyard complaints ending up in court raises questions about how schools will shoulder the costs.
The Ombudsmen's Office already fields dozens of official school-related complaints each year from aggrieved parents and students - a number staff say is increasing.
Among them are disputes over teacher conduct, missing class time for religious instruction, students having to buy school stationery, and schools' failure to address bullying.
Costly task
Schools are now faced with the prospect of hefty legal bills to tighten up potential loopholes in their rules around students' appearance.
Secondary Principals Association president Tom Parsons said schools would now have to "lawyer up" simply to ensure existing rules passed the legal test set by the High Court.
"One of the unintended consequences [of the ruling] will be the expense school boards have to go to ensure [rules] are watertight."
New Zealand School Trustees Association (NZSTA) president Lorraine Kerr says the Battison ruling will set a precedent.
"Boards will either need to be legally savvy or find more money for lawyers."
This is no easy task, considering most school boards are already "screaming" for money to cover even the basics.
Ms Kerr says the intention of school rules is to uphold the culture of the school, and keep all students and staff safe.
NZSTA fields complaints about school rules from both students and parents, often raising questions about responsibility.
"Schools, unfortunately by default, tend to wind up with all society's woes. Bullying is a classic example. [In] one case there were two girls bullying off school grounds, but they were in school uniform. Whose responsibility [is it]?
"I know that boards and principals in New Zealand feel responsible in terms of those kids that come to school without breakfast [and] what can the school do in terms of supplying raincoats."
Schools sometimes have to step in where parents don't.
However, at the very least the ruling should encourage schools to review their policies, making sure they're current and relevant.
"I'm hoping that common sense will prevail and that boards will look at how robust their policy review system is."
The law
According to YouthLaw Aotearoa everyone in New Zealand can express themselves however they like, as long as it's reasonable.
This idea of "reasonable" changes at school, however, and the piercings, hairstyles and cultural tattoos that are acceptable in society often no longer comply with school rules, the organisation's website says.
But rules that limit freedom of expression can't just be "made up" by teachers and principals. They have to be written down and agreed to by the school's board of trustees.
Independent body
YouthLaw managing solicitor Vanushi Walters says the free legal service helps about 350-450 children and young people every year with education-related matters.
Most cases are contesting suspensions, but complaints about discrimination, enrolment problems and special needs requirements also make up a large chunk. "We deal with a large number of calls each week from young people and their parents who feel the balance of power is significantly weighted against them," she says.
"In some cases young people face what they feel is excessive disciplinary action, in other instances they feel the action being taken against them is discriminatory."
In the worst cases parents are given an ultimatum - "withdraw your child or they will be excluded".
Many students and parents don't realise they can challenge the school's discretionary powers.
But this is beginning to change, and the number of students approaching YouthLaw has increased in the last year, Ms Walters says.
"There's certainly more questioning about whether the board is exercising their discretionary powers within the scope of the law."
Ms Walters says there is "huge" value in keeping kids in the education system instead of passing the buck to the community and the youth justice system.
"We have to remember that once these kids are out, they are often out of school for long periods."
YouthLaw wants to see an Independent Education Appeals Authority set up for students who have been suspended or excluded from school.
The authority would review decisions made by school boards to keep their "significant" discretionary powers in check, Ms Walters says.
"At present the only recourse for students and their families when they disagree with a decision is to apply to the High Court for judicial review. This is so expensive it is financially out of reach for most families and is extremely time consuming."
Complaints to the Ombudsman and the Human Rights Commission are free but a response can be "extremely slow".
Neither has the power to change a school decision and can only make recommendations - not a practical remedy for students who need to be enrolled at school, she says.
Case for an authority
One group of students who could have benefited from an independent body were the victims of extreme violence at Hutt Valley High School.
In 2007, a gang of six teens terrorised younger boys at the Lower Hutt school, subjecting them to sexual abuse in a series of harrowing attacks.
School authorities at the time failed to protect the victims, alert parents or report the attacks to police, instead choosing to stand down the culprits for a few days.
After learning of the attacks and trying to deal with the school, parents eventually complained to the Human Rights Commission and Ombudsman's Office.
An Ombudsman's Office report released in 2011 found the school had a history of failing to punish culprits or acknowledge the seriousness of their crimes.
In an Ombudsman's Office report released in 2001, Ombudsman David McGee lambasted the school's response to the "premeditated, systematic assaults", calling its discipline policies inadequate and highlighting its failure to implement Education Ministry child abuse policies.
The school now has a new principal and board chair and has been proactive in making significant changes to address violence and improve the safety of pupils and staff.
Complaints
The Ombudsman's Office received 64 official school-related complaints last year, and has fielded 39 this year so far.
Most of these were lodged against school boards for their treatment of students. Complaints varied from disputes over appearance to cultural differences clashing with school policy.
Complaints could also have a ripple effect, sometimes unearthing hundreds more through the process.
In one case, a complaint was lodged over "insufficient support" for a student with special needs, while another family complained of being "unlawfully" invoiced by the school.
School bullying accounted for a significant proportion of the complaints. However, not many made it right through to the final investigation stage, and those that did could take months to resolve.
