But after King's decided to allow Year 11 girls to enrol this year, their exemption was scrapped by College Sport. If King's court challenge is unsuccessful, they will have to abide to the full "New to School" restrictions from 2018.
King's headmaster Simon Lamb revealed the legal challenge in an email sent to students' parents and guardians stating he felt the change to the rule was "inconsistent with Auckland College Sport's own objectives".
He wrote the school had "filed an application for judicial review" of the decision to drop the exemption, and expected the matter to be heard by the High Court "mid next year".
"King's College fundamentally believes that all students, no matter what gender, should have the right to choose which school they wish to attend and should not be penalised from playing premier sport. We do not engage in 'poaching' girls into the College to fill premier sports teams."
In a statement to the Weekend Herald, Lamb said enforcing the rule could have ramifications to some of his school's new female students.
"This could potentially impact girls new to King's from 2018 who wish to participate in premier sport," he said.
"The original bylaw was put in place to prevent improper poaching of students playing in premier codes; which King's College absolutely respects."
King's College has a roll of 1025 students, including 171 girls.
Quotas for premier teams under the "New to School" rule differ depending on the code and squad size. A school is allowed to have four new-to-school students in first XI football, hockey and premier netball squads, but a maximum of six are permitted in 1st XV rugby teams.
Students are considered new to school if they move from one school to another from the first day of term three in Year 9.
College Sport chief executive Jim Lonergan said premier school-grade athletes were typically in their final two years at school, and said admitting students in Year 11 will "enable King's to invest similar amounts of time and coaching in these students as is the norm for all other schools that compete in premier sports events".
He would not discuss potential ramifications if the legal bid from King's College was successful, including if he feared it could provide a precedent for other schools to challenge the bylaw.
But in a statement, Lonergan told the Herald the priority for the sporting body was on reaching a compromise.
"We really do want a resolution before it reaches court," he said.
Lonergan said College Sport had offered a "further significant concession but to date King's has been unwilling to compromise".
Lonergan refused to reveal what the potential compromise was.
When King's College was asked for details on the concession that was offered, a spokeswoman for the school directed the question to College Sport.
Last month, the Herald highlighted the growing trend of the Year 14s, students who shun university or jobs to return for an extra year of school and another season of premier sport.
The investigation covered the scouting and recruitment of intermediate school students, the rise of independent schools as sporting powerhouses, and the trend towards students staying in school for an extra year.
The reasons for returning for another year of study include the opportunity to play in a higher grade based on performances in the previous year and it provides a further chance to earn NCEA credits.
Schools benefit by the potential for success of teams with Year 14s, which in turn helps to create a strong sporting culture and improve the school's public image.
What is College Sport?
• Sports body which coordinates sport for 107 secondary schools in the greater Auckland area
• Works directly with the sports department of all 107 colleges
• It covers 45 different sporting codes
• About 200 sports coordinators are involved in College Sport events and competitions
• More than 100,000 students participate in College Sport-sanctioned tournaments
• Is a charitable entity established in 1989 by the Principals of Auckland, to assist in the delivery of interschool sport to their member schools
