The Teachers Council is standing by a change it has made to the profession's disciplinary code, that teachers fear may lead to an unfair intrusion into people's private lives.
The new rule, which came into force on Friday, allows the council to censure for "any conduct that brings or is likely to bring discredit to the profession."
The move has been criticised by at least two unions representing teachers.
Teachers Council director Peter Lind, says sometimes actions in a teacher's private life do have an impact on professional responsibilities.
But he says no decision on any complaint would be made without a thorough investigation, and parties would be able to present their case before any final decision was made.
New Zealand Educational Institute president Frances Nelson says teachers were previously judged solely on their teaching practice.
She says the new clause is unclear and lacks boundaries.
Ms Nelson says the majority of teachers have nothing to fear from the new rule.
However, she says the NZEI is advising teachers to be sure they can justify "extreme things" that might happen in their private lives.