The Secondary Principals Association is warning its members they could breach the Human Right Act by not allowing students to take same sex partners to school balls.
In 2011, a Wellington pupil was told he could not take a former student to the St Patrick's College.
Association president Tom Parsons highlighted the issue in a newsletter to principals on Thursday.
Mr Parsons outlined possible unlawful discrimination under the act if students were stopped taking a same sex partner.
He said the reminder was directed at new principals in particular to clarify the issue and prevent any adverse effects before they happen.
