The Secondary Principals Association says it has now confirmed schools have the right to legally search pupils for a weapon, if they feel there is an imminent threat to the safety of staff or students.
The association has released a draft search and seizure policy to its members, after seeking legal advice over teachers' disquiet that they may be charged with assault if they conduct a search.
The move follows a rise in violent incidents in schools, including the stabbing of a teacher, allegedly by a 13-year-old boy, at Te Puke High School in May.
The association's president, Patrick Walsh, told Nine to Noon the advice will act as a deterrent to a minority of students who are thinking of bringing weapons to school.
Youth rights activists are unhappy with the search and seizure draft policy released by the association.
Senior lawyer from Youth Law, John Hancock, says it only outlines the process a teacher should undertake for the seach, and doesn't mention under what grounds a search should take place.
He says students could be pressured by a teacher into consenting to a search.