A school principal has been censured for suspending a child informally without following the proper rules - a common process that has been called "Kiwi suspension".

The principal of Onewhero Area School south of Tuakau, Greg Fenton, kept the 10-year-old boy at home informally for almost three weeks after the boy touched three girls in the chest and genital areas.

The Teachers Disciplinary Tribunal has censured Fenton because he did not suspend the boy formally, triggering a board of trustees meeting, until 13 school days after he suspended him informally.

Fenton is no longer at the school and the tribunal has directed that he "shall not resume a position of principal unless he has undergone a mentoring programme".

The decision represents a rare challenge to the common practice of "Kiwi suspension" and appears to set a legal precedent.

Youthlaw found in 2016 that there had been "a dramatic rise in the caseload related to informal removals since 2013", at the same time as a decline in reported formal suspensions.

The boy in the Onewhero case had been the subject of a report by a mental health service, although the tribunal said Fenton only became aware of this at the board of trustees meeting about the boy's suspension.

Three girls in the boy's Year 6 class complained to their teacher on October 28, 2016, that the boy had " poked and prodded" them and subjected them to "unwanted attention".

"This had been directed at one girl in particular, and [the boy] had described her as his girlfriend on several occasions," the decision states.

One of the three girls was the best friend of Fenton's own daughter.

On November 7, the father of one of the girls emailed the deputy principal complaining of "inappropriate comments" made by the boy to his daughter.

Later that same day, the three girls spoke to a person whose position has been deleted and said the boy was "coming over into their space", "annoying them", and wanted to be the boyfriend of one of the girls.

Fenton then spoke to the three girls together and asked them to describe what had happened.

"He said that each girl described that over the course of several weeks [the boy] had touched her chest area and genital area," the tribunal said.

The next day Fenton met the boy's parents and "said he would like to try and avoid suspension and that he felt that CYFS [Child, Youth and Family, now Oranga Tamariki] were the right people to get involved". He asked the boy's parents to keep their son at home until the investigation was completed.

CYFS found that the boy's problem behaviours only occurred when a person whose position has been deleted was not present in the class.

"CYFS considered the actions were of a boy [deleted], encouraged by peers in his class, and that the girls were humiliated by the class who found the conduct hilarious to watch," the tribunal said.

"The CYFS representative noted that when Child's [deleted] was present there was no issue, and that the situation was a classroom management issue.

"CYFS considers that the conduct involved touching over clothes, that it could not be deemed sexual assault, and that there had been no penetration."

The agency concluded that "it was inappropriate for [the boy] to be out of school".

On November 22, the boy's mother "asked the school about his [deleted], which were allocated to the school to be used for [the boy]".

"She arranged to bring him to school to work with [deleted] on November 28, at which point [Fenton] handed her a formal suspension letter," the tribunal said.

The formal suspension triggered a board of trustees meeting, which by law must be held within five school days, on December 2.

The board asked for more information and adjourned for an hour and a half so that Fenton could contact the Ministry of Education's crisis intervention team. Fenton told the board that the crisis team would get someone to the school on the following Monday or Tuesday, December 5 or 6, so the board agreed to meet again late on December 6.

However, the crisis team told Fenton at 8.30am on the Monday that it could not get to the school until the Wednesday. A visit was arranged for 8.15am on that day, December 7.

The tribunal found that Fenton "did not inform [the crisis team] that in fact there was a disciplinary hearing for the Child's case on the afternoon of December 6", and "did not then advise the chair of the board or any other member of the board of trustees that the crisis team meeting would not have taken place before the disciplinary hearing on December 6".

The board met as scheduled on December 6 and decided to exclude the boy - removing him from the school permanently.

"When Child's mother queried the decision, stating that she thought the crisis team's assistance had been sought to help the board make a decision, [Fenton] stated that he advised the crisis team of the timeframe the school was working to," the tribunal said.

The tribunal concluded that Fenton's actions were "dishonest" and "unethical" and constituted "serious misconduct".

It censured him and ordered that he should not resume a principal's position unless he underwent a mentoring programme of at least six months covering "management of students and training in being a principal, conflicts of interests and balancing competing rights of children".

Youthlaw general manager Jennifer Braithwaite said she was not aware of any other cases where a principal has been censured for informally and illegally suspending a child.

"However, Youthlaw does see cases where schools have asked students to not be in class and stay at somewhere like the principal's office/office area whilst an investigation is ongoing, and the parents have been unhappy with the school and decided to take the children home themselves," she said.

"We also see cases of 'Kiwi suspension' or where principals have suggested to students and their families that the student voluntarily withdraw before they are formally disciplined.

"This particular case appears to be a particularly bad example in that the principal was both aware that his actions were unlawful and was not honest in his dealings with the child's parents or the board.

"It is good to see that the Teaching Council has treated it with the seriousness that it deserves given the damage caused to the student's wellbeing and education."