The National Association of Head Teachers (NAHT), whose annual conference opened in Torquay, may seek a test case in order to see whether a school could expel the children of difficult parents.
Teachers are now twice as likely to be attacked by other adults as by children, according to figures compiled by the association.
In the past year 16 NAHT members suffered serious physical assaults by parents, two by members of the public and nine by pupils.
Yesterday David Hart, the association's general secretary, said talks with other teachers' organisations had confirmed that the figures were representative of the national picture.
Officials at the Department for Education and Employment had told him that it would be legal to exclude pupils because their parents were violent, he said. However, the decision might be overturned by an independent appeals panel and a test case was needed.
He called for government action to allow the panels to consider the greater good of the school rather than simply the interests of the child.
In two recent cases, one in Nottingham and one on Tyneside, teachers threatened to strike when a violent child was returned to school after an appeal.
"If an assault has been committed then the relationship between the school and the parent might be reduced to zero. The child might have a better chance of a fresh start in another school," he said.
Yesterday the NAHT's incoming vice-president, Liz Paver, of Intake First School in Doncaster, described how a normally supportive mother had left her with a broken tooth and injuries to her knee and hand after a dispute.
The woman went into the school to remonstrate with an older child who had accidentally bashed her four-year-old daughter in the mouth in the playground.
The head followed the woman out to her car to talk to her, and as she leant in through the window she drove off, dragging Mrs Paver along with her.
The mother, who was a member of the school's parents' association, and whose husband was a governor, later apologised, but Mrs Paver said in other circumstances the dispute might not have been resolved so easily.
"We are spending 90 per cent of our time dealing with 2 per cent of our pupils and 2 per cent of our parents and that cannot be right.
"We have to grasp the nettle and say if someone cannot accept our code of practice they will be put out," she said.
The association has pressed ministers to make it easier for schools to prevent parents from withdrawing their children from detentions as well as for reform of the appeals panels and more powers for head teachers to exclude pupils.
Last night, the National Confederation of Parent Teacher Associations called for a meeting between ministers, teachers' unions, social services and parents to discuss school discipline. Its spokeswoman, Margaret Morrissey, sympathised with schools but said national action was needed.
"It is outrageous to blame this on people who probably don't have the power to resolve it without support," she said.Reuse content