Two pupils, expelled for their allegedly violent behaviour, will take their case to be allowed back into normal lessons to the House of Lords this week.

The two, who cannot be named for legal reasons, were expelled from different comprehensives in the south of England but were allowed back following successful appeals.

Teachers from the schools in Hertfordshire and south London voted to refuse to teach them and they are currently being taught in isolation from their peers.

Cherie Booth QC, wife of Prime Minister Tony Blair, is representing one of the youths in the landmark case which will decide whether teachers can boycott violent pupils - even if they have are legally entitled to be in school.

Final bulwark

The case centres on whether the teachers' vote to refuse to teach the pair was valid under union law.

The teachers' union, the National Association of Schoolmasters Union of Women Teachers, has already successfully argued in the High Court and the Court of Appeal that the vote was legal as it related to the teachers' conditions of employment.

Commenting on the case NASUWT general secretary Eamonn O'Kane said: "These cases are of crucial importance to teachers since they concern their right to refuse to teach pupils they believe are a threat to themselves and other students.

"The support of their union is the final bulwark which the teachers rely upon in order to protect themselves against the effects of violent and disruptive pupils.

"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."

The hearing before the Law Lords is due to begin on Monday and is expected to last three days.