CHERIE Booth will next week defend the rights of an excluded teenager in a landmark case to determine whether teachers can refuse to teach violent puils.
The Prime Minister's barrister wife will present the 17-year-old's case to the Law Lords.
It is one of two cases being heard by the House of Lords in a three-day hearing starting on Monday as the Government attempts to crack down on violent and disruptive pupils.
Both involve members of the National Association of Schoolmasters Union of Women Teachers and pupils returned to schools by appeals panels.
Ms Booth's interventions could be particularly embarrassing for her husband's Government, which has been taking a tough line on violent students.
Last month Estelle Morris, the former education secretary, told the Labour party conference: "Teachers cannot teach if children are disruptive. One child threatening or abusing a teacher in one of our schools is one too many. One child showing just disrespect to a teacher is one child too many."
Ms Morris made a bungled attempt to intervene in the reinstatement by an appeals panel of two teenage pupils at Glyn technology college in Surrey who had threatened to kill a teacher. The two boys are still not at school.
Education Secretary Charles Clarke has said that he is determined to crack down on the "malcontents" in the classroom. However, unlike his predecessor, he is not seeking powers to intervene in exclusions from Whitehall.
Ms Booth will be representing a teenager excluded from a Hertfordshire secondary school in January 2001 for punching and kicking a fellow Year 11 pupil so badly that he needed hospital treatment.
The boy, who cannot be named for legal reasons, was excluded but returned by an appeals panel. When teachers threatened industrial action if he was returned to mainstream classes, the head and governors offered one-to-one education in the school.
A legal challenge by him was lost in the High Court and later in the Court of Appeal.
The second case involves a boy excluded following a long period of violence, physical threats and verbal abuse of teachers and pupils during Years 9 and 10 at a London secondary.
He too was reinstated by an appeals panel. Again, the NASUWT balloted for action.
A legal challenge by his mother suggesting the ballot for action was not over a legitimate trade dispute was rejected by the High Court and the Court of Appeal.
Eamonn O'Kane, general secretary of the NASUWT, said there would be an exodus from schools if teachers lost their ability to refuse to teach violent students.
"Removing that defence will send an unmistakable message that teachers are powerless in schools in the face of behaviour that will undermine the education of the great majority of well-behaved students," he said.