Three years ago, when the National Party announced its plan to make all primary schools test pupils' ability in reading, writing and mathematics, teachers were scornful. Their union, the New Zealand Educational Institute, suggested this amounted to no more than fine-tuning of what was already being done. If such were the case, the introduction of national standards would surely entail negligible disruption.

Of course, the NZEI was playing down the scope and importance of what will be a widely welcomed assessment programme. And, now, it is going to another extreme in trying to stop or, at least, stall its start next year. The union, in league with the Principals Federation, says the standards are being rushed and schools, already dealing with an overhaul of the national curriculum, need more time to prepare. It has asked for a trial period, doubtless hoping this will diminish the chances of a nationwide introduction.

More ominously, the unions have threatened boycotts and industrial action, and last week wrote to principals urging them to ask school boards to voice the same concerns. Understandably, the Minister of Education, Anne Tolley, is vexed. She has responded by saying that in "extreme" cases where schools allow teachers to boycott the standards, she will dissolve the board - because the trustees would be refusing to obey the law - and replace it with a commissioner.

The minister has strong arguments to support her stand. Most fundamentally, National's policy was put to the electorate at the last election. It comes with the stamp of democracy. Teachers unaccustomed to such assessment matters being imposed upon them need to acknowledge that this one has the support of most parents - who will benefit from a clearer understanding of their children's progress - as well as the School Trustees Association.

Schools have had time to prepare. The Ministry of Education has held meetings about the standards since the middle of the year. Mrs Tolley has accommodated many of the teachers' practical concerns. When it became obvious some schools would struggle to be ready, plans to fully introduce the standards next year were abandoned. Schools will not have to report to officials on pupils' performance against the standards until 2012. But parents will still have to be told how their children are performing from the start of next year.

Sympathy for teachers is often based on their heavy workloads. But their contention that the testing and reporting requirements will be a burden that dictates a lesser focus on the curriculum overhaul does not bear too much scrutiny. If reprioritisation is necessary, it should be done. The curriculum revision, which is proceeding at a sedate pace, can take a back seat while the more important issue of effective assessment is tackled.

Mrs Tolley is surely right to suggest the unions' arguments are now purely philosophical. This has underpinned their resistance from the start. It has endured despite the Government concessions and despite the public support for national standards. It is the only reasonable explanation for the dragging of feet and the increasingly radical demeanour.

The Schools Trustees Association has made clear its distaste for the letter from the unions trying to influence boards. It is, it says, irresponsible and unprofessional to incite boards to act as principals' mouthpieces. Any that succumbed would have forgotten their duty to parents.

Similarly, teachers have a responsibility to heed the policy of a democratically elected government. That is a lesson they, and their unions, seem to have yet to learn.