A South Auckland landlord who illegally rented an unconsented garage to a young family was deliberate and cynical in his actions, investigators say.
Satya Silan is the first landlord to be successfully prosecuted under the government's new tenancy laws.
The Tenancy Tribunal has ordered him to refund nearly $16,000 in rent and pay $750 in exemplary damages for renting the garage as a home to a family with a young child.
The tribunal found he failed to provide a warm, dry, safe home.
The Ministry of Business Innovation and Employment, which took the prosecution, said it was not the first time Mr Silan had rented the garage and he had ignored warnings from Auckland Council.
The prosecution is the first under a 2016 law that allows the government, rather than tenants, to prosecute bad landlords.
Tenancy Tribunal compliance and investigation manager Steve Watson said there were no smoke alarms in the garage, which Mr Silan was renting out for the second time.
"We deemed that to be quite a serious matter.
"Landlords are running a business, and running a business had obligations and responsibilities."
What Mr Silan did was a "deliberate and cynical breach", Mr Watson said.
Mr Watson hoped the prosecution sent a message to landlords to remember their obligations.
"The team is really happy that justice has been done for this tenant, but what really motivates them is lifting the quality of the tenancy system and making the tenancy experience better for vulnerable people."
Since the ministry set up an investigations unit, it has received 242 complaints and found more than 200 of those involved a breach of tenancy law.
However, it would not prosecute every case and would instead try to encourage landlords to improve conditions, Mr Watson said.
"In most cases, our intervention is enough to get landlords to comply."
Building and Construction Minister Nick Smith said the prosecution sent a strong message to landlords that properties should not be tenanted unless they were warm, dry and safe.