To do so is, strictly speaking, industrial action (which is subject to detailed rules on balloting, notice etc). However, sometimes an incident is so serious that staff may collectively consider refusing to teach the pupil concerned.
Under health and safety laws your employer has a legal duty of care towards you as well as to the students and if they knowingly put an employee's safety at risk they could be in breach of that duty of care.
In 2003, the House of Lords handed down two rulings with important implications for violence in schools. The first ruling upheld the right of unions to ballot members over refusal to teach a violent and/or disruptive pupil. The second ruling upheld the right of a school to make alternative provision for a pupil who had been reinstated following a successful appeal against exclusion to an independent appeals panel.
Government guidance on this issue is available: Behaviour and discipline in schools: a guide for teachers and school staff.
Refusal to teach is an industrial action; a weapon to be used only as a last resort - with careful advice from ATL. However, ATL does ballot members to refuse to teach when it feels their safety is at risk.
A headteacher/principal has the power to exclude violent or seriously disruptive students either for a fixed period, or permanently (subject to the student's right to appeal).
Responding to difficult or disruptive behaviour is a challenge for all teachers. ATL can always help with strategies and suggestions that may help.
Returning from exclusion
Figures published show that, although there were more than 5,000 assaults on pupils and teachers in Scotland in 2005, only two per cent ended in permanent expulsion. Assaults on staff are unacceptable and health and safety measures in schools and colleges must be proactive not reactive.
ATL considers it unreasonable to reintroduce a disruptive or violent pupil without the employer first conducting a risk assessment and actioning additional preventative measures; simply 'hoping for the best' will not do.