Teaching unions have welcomed the decision to clear headteacher Marjorie Evans of assaulting a disruptive pupil.
The National Union of Teachers, which financed Mrs Evans’ case, said it was a “landmark judgement.”
A spokesman said teachers across England and Wales would be celebrating.
The NUT called on the government to offer teachers greater protection against allegations of heavy-handedness.
Monmouthshire headteacher Mrs Evans had been convicted of slapping an unruly 10-year-old boy, who suffers from an attention disorder, whilst attempting to restrain him during a violent episode.
But she was cleared at an appeal on Friday, and claimed there had been a plan to damage her good reputation with malicious allegations.
Accusations of violence by teachers against pupils are rising, according to the Association of Teachers and Lecturers.
NUT General Secretary Doug McAvoy said: “The case demonstrates how vulnerable teachers are.
“They need greater protection, and that requires that their professional judgement to exclude a pupil must be upheld.”
The Secondary Heads Assocation also welcomed the decision.
General Secretary John Dunford said: “I am very pleased to hear she has been found not guilty.
“A jail sentence seemed completely inappropriate, even if she had been found guilty.
“I think this will raise public awareness of the difficulties teachers are faced with when dealing with disruptive pupils – it is a debate we need to have.”
‘Not corporal punishment’
The NUT has said it will issue new guidelines to teachers on dealing with pupils with behavioural problems.
The union’s Secretary in Wales Gethin Lewis said: “This is not about corporal punishment.
“This is about how teachers and headteachers carry out their lawful work of running a school with a minority of disruptive children.”
Monmouth MP Huw Edwards has written to Education Secretary David Blunkett about the implications of the case for the teaching profession.
School Standards Minister Estelle Morris said the appeal outcome was “a sensible decision”, and said the government had already issued guidelines to schools on handling unruly students.
But Nigel de Gruchy of the National Union of Schoolmasters’ Union of Women Teachers called for problem pupils to be dealt with.
He said: “I think it is very welcome news and I just hopethat, in future, youngsters who assault teachers are treated with equal severity by magistrates.”
Welsh Secretary for Education Rosemary Butler said that the National Assembly had committed itself to carrying out a review of theexisting guidelines on restraint of children.
The review will be undertaken with teh Department for Education and Employment and the Department for Health.
Marjorie Evans attracted vocal support from teaching professionals during her case.
She told the court that the boy was trying to punch, push and headbutt her.
Mrs Evans, who had been suspended from her job, said she wanted to return to teaching.