The Ministry of Education has begun ordering schools opposed to the national standards to start using the benchmarks in reading, writing and maths.
Opponents say the move is a significant escalation in the battle over the standards.
Several hundred schools are refusing to put the standards in their charters and, until now, the ministry has been asking them to rethink their stance.
But on Wednesday, Island Bay School in Wellington received a letter ordering it to include the standards in its charter by 2 September. It is believed to be the first to receive the order.
Board of trustees chair Jane Forrest says the ministry is breaking the law because it must negotiate any changes to the charter, and the school will defy the order.
"I'm asking them to suspend taking the action ... until there is a genuine opportunity to negotiate, as is required."
Ms Forrest says she is surprised and disappointed by action.
The ministry says it will use statutory intervention, where required, to ensure that boards comply with the Education Act.
