Teachers could be asked to swear an oath against inappropriate relationships with pupils.
A motion due to be considered by Flintshire council could see teachers and school staff pledge in front of a manager not to form intimate relationships with students.
It follows the court case of Gwynedd headteacher Neil Foden, who was jailed for 17 years in July after being found guilty of sexually abusing four girls.
But education union NASUWT said introducing the oath, which will be discussed at a full council meeting in Mold on Tuesday, would show a shocking contempt for teachers.
The motion was submitted by Hope councillor Gladys Healey, who claims stronger measures are needed to protect children from abuse by teachers.
Neil Butler, the union’s national official for Wales, said: "This motion serves only to bring the teaching profession into disrepute.
"Teachers in Wales are highly regulated and have to adhere to the Education Workforce’s code of practice which explicitly states that teachers 'have a duty of care for the safety, physical, social, moral, and educational wellbeing of learners and young people'," he added.
“If a teacher falls short of this code, they face disciplinary action and potential dismissal.
"For Flintshire council to introduce its own oath would be showing a shocking contempt for the profession."
A child practice review is currently being carried out by the North Wales Safeguarding Board following Foden’s sentencing, which local authority Cyngor Gwynedd has pledged to co-operate fully with.
The board’s chair described it as a "vital step in protecting vulnerable children in north Wales".
However, critics fear that it will not go far enough.
Ms Healey, who sits on Flintshire’s education scrutiny committee, said current safeguarding measures need improving
"The council acknowledges that, even with safeguarding training and the code of professional conduct and practice established by the Education Workforce Council in Wales, there are still cases of child abuse by teaching professionals and cases of teachers forming inappropriate relationships with pupils and students for whom they are responsible," the Labour politician said.
"The council deplores the formation of such relationships and actions which abuse children and bring about a loss of their childhood innocence."
If approved, all staff working in education settings in Flintshire will be required to swear the oath, along with any future employees.
The Association of School and College Leaders (ASCL) has said it would be willing to discuss the proposal.
Claire Armitstead, director of ASCL Cymru, said: "We share the horror felt at the case which has given rise to this motion, and are always ready to consider any proposal aimed at improving the safeguarding of young people.
"We would welcome the opportunity to discuss this further with councillor Healey.
"There are strict professional and legal regulations in place, and anyone found guilty of an inappropriate relationship can face disciplinary and criminal action."