The united front displayed by classroom unions during last week’s strike was unprecedented, many argued proudly. But now that teachers have returned to the workplace, it appears the deep splits within the union movement are beginning to reopen, with a serious legal dispute between teachers’ and heads’ representatives.

The row centres on the NASUWT’s “work to rule” campaign, dubbed the “quiet revolution”. Indeed, general secretary Chris Keates has insisted it was designed to be “pupil, parent and public friendly”.

Citing concerns about teachers’ workload and job losses, as well as the pensions overhaul, the union’s members have been issued with lists of duties they should not be performing. Supervising pupils at lunchtime, invigilating public exams, covering for absent colleagues and attending unscheduled after-hours meetings are among the tasks NASUWT members have been told to abstain from.

But, while more than 220,000 NASUWT members were balloted on the industrial action, it is unclear how many are taking part. Indeed, several contributors to TES forums have claimed it is business as usual for their colleagues in the NASUWT.

To make matters worse, heads’ union the NAHT has raised “significant concerns” about the impact of the action on school leaders. Most worryingly for NASUWT members, the NAHT says teachers could still face disciplinary action because the ballot offers them only “limited protection” when they refuse to work.

Legal advice produced by the NAHT insists the union is “not aware of any body of evidence” supporting claims that, nationally, teachers are being denied their contractual rights.

“NAHT has significant concerns about the NASUWT action short of strike action, as those who will be most affected (school leaders and governing bodies) are not in a position to resolve the dispute,” the document says.

“Headteachers may need to issue an individual teacher with an instruction to carry out a particular duty and to seek confirmation that the teacher is refusing to comply . It will then be for the employer to determine whether a breach of contract has occurred and the appropriate remedy,” the guidance adds.

But the NASUWT says taking part in industrial action is a “legal entitlement” for its members. “The NASUWT has taken detailed legal advice to ensure that its ballot and proposed action meets the provisions of the legislation and therefore members are protected by the lawful ballot,” its own advice says. The union adds that it will “strongly defend any members who are threatened”.

But the interpretation of the guidance varies from school to school, says Association of School and College Leaders president Joan McVittie, who is also head of Woodside High School in north London.

“For the most part, schools which have fully embraced the workforce reforms should be okay. There are no ripples at my school at the minute, but there are some extreme positions being taken by school reps,” she said.

And NUT deputy general secretary Kevin Courtney said that it would not follow the NASUWT’s lead, but would continue its strategy of targeting schools where workload issues emerge. “Wherever NUT members find workload issues, we want them to come to us and we’ll back them,” he said.

Professor Howard Stevenson, an expert in education industrial relations at Lincoln University, warned that the imprecise nature of teaching contacts and regulations could make it difficult for teachers to decide what duties they can safely refuse to carry out.

“There are inevitably going to be differences in interpretation, both by union members and by the heads. It is going to be down to whether union members will be prepared to stand up to their head, and how strongly represented the NASUWT is in their school,” he said.

While the NASUWT has been accused of dragging its feet in getting involved in the pensions campaign, on the issue of teachers’ workload, at least, it is keen to be seen to be taking the lead.

While the “work to rule” campaign could result in a significant improvement in teachers’ work-life balance, it could equally end in a humiliating climbdown for the union. And it is the strength of support from NASUWT members up and down the country that will decide the outcome.

NASUWT MEMBERS SHOULD REFUSE TO .

Teach their timetabled lessons unless they receive a minimum of 10 per cent guaranteed PPA time.

Carry out any other activities in their designated PPA time.

Implement school policies that have not been evaluated for impact on workload.

Cover for absence.

Attend meetings and activities outside school hours that are not on the school calendar.

Supervise pupils during the lunch break.

Invigilate any public exams, including GCSEs and Sats.

Undertake administrative and clerical tasks.

Be observed teaching by anyone who is not a qualified teacher.

Accept any classroom observation not agreed in their annual performance management review.

FROM THE FORUMS

I have a confession to make. It’s only day one and I’ve failed. I may have put a blue border up on one of my displays. I know, I know . I feel so ashamed.

alrightmebabbers

In my school the NASUWT members who are worried about their careers are not working to rule, and the ones who have informed the head they intend to work to rule have been told to think very carefully about their reputations and future opportunities.

newposter

I am trying my best to work to rule, but in a school that needs to move forward (or face special measures) I am finding many conflicts of interest, as some things I refuse may have a detrimental effect.

sarah125

It is impossible to work to rule when only one union is involved. It has to be a joint effort and a really strong plan has to be devised that works in every school.

ellie_ellins

None of our NASUWT (members) are doing it.

walnuthead

I work in an academy, which seems to be inherently more dangerous when considering such action. I agree with the principle, but how will it work and what will it look like?

Neville28

Join the debate at www.tes.co.ukforums.

Original headline: Heads’ legal warning could silence union’s `quiet revolution’