The EIS says the Labour-controlled authority has introduced a grievance and disciplinary code for all staff that effectively tears up the separate agreement for teachers inherited from Strathclyde Region.
"There was no consultation and no discussion," Ken Wimbor, the institute's assistant secretary, said. "We were given the unique explanation that the new procedures were in force but out for consultation. When they refused to drop the inclusion of teachers to allow discussion, we were left with no option but to go to law."
Alan Cuthbertson, South Lanarkshire's director of personnel services, says the council has had "no formal response in writing from the union indicating what their concerns are". He added that teachers' terms and conditions relate to a national agreement which stipulates that disciplinary and grievance matters must be "in accordance with the local procedure".
Mr Cuthbertson added: "The procedure we are applying is one which has worked satisfactorily for a considerable number of council staff for a considerable time and we are applying it with a greater degree of consistency."
The South Lanarkshire dispute reflects the desire of a number of councils to harmonise conditions and irritation that teachers have separate agreements and negotiating rights. The convener of South Lanarkshire's personnel committee is the powerful Pat Watters, an influential management figure in national bargaining with other council employees.
The EIS is concerned that "what South Lanarkshire does today, other education authorities may do tomorrow".
All other authorities are allowing cases involving possible dismissal to be decided by a straight majority of the education committee, whereas South Lanarkshire insists on dismissal by heads of department followed by a right of appeal to the personnel services (applied conditions of service) subcommittee. Mr Cuthbertson argues that this is in line with the code laid down by Acas, the conciliation and arbitration service.
The previous system allowed no internal right of appeal once a decision to dismiss had been taken. The revised procedures also allow for suspension without pay as an alternative to dismissal.