Te Whanau O Waipareira Trust goes to court on Monday, to argue the Crown was wrong to axe one of its welfare contracts.
The trust is bringing the case against the Ministry of Social Development - which says the delivery of the Family Start programme to at-risk families was not good enough.
But the trust says the ministry wrongfully terminated the contract, wrongfully used its powers and acted in premeditated bad faith.
The trust says it's been running the Family Start service for 14 years.
The contract covers 270 families and supports families in the first three years after a baby's born.
The case will be heard at the High Court in Auckland.