The Supreme Court will have the final say on whether care workers are entitled to the minimum wage.
Wellington woman Jan Lowe was a relief caregiver for disabled and elderly people.
Because she was paid a "subsidy" of $75 for 24 hours of care work, it worked out to $3 an hour.
Ms Lowe is backed by E Tu Union and originally won her case in the Employment Court, which said she was entitled to minimum wage and holiday pay.
That was overturned in the Court of Appeal, where the Ministry of Health and District Health Board argued Ms Lowe wasn't their employee.
The Supreme Court is now tasked with making a final ruling on the matter.
Speaking outside court, Ms Lowe said she was hopeful "injustice and unfairness" wouldn't be allowed to prevail.
She said the pay rate hadn't changed since she started the job in 1991.
"I don't know of any other organisation in New Zealand that could get away with paying $3 an hour for hard work.
"The first job I had was a husband and wife, both with Alzheimer's.
"They would both get up in the night, both wander around, both didn't know where they were.
"I still got the same $75 for 24 hours for both people."
In court, Ms Lowe's lawyer Peter Cranney said the care workers were working for DHBs and the Ministry of Health, no matter how that was legally labelled.
"It could be a sale and purchase agreement, it could be a contract for services, but certainly both of those would mean they've engaged her.
"I take the rather simple view that you're engaged if you're doing work that someone else is paying for.
"The sort of employment we're talking about here is not Rolls Royce.
"They're really in the situation of a casual McDonald's worker, who nonetheless are entitled as employees to receive the minimum wage."
Lawyer for the Ministry of Health and Capital and Coast District Health Board, Joanna Holden, said it wasn't a typical employment relationship.
"The intention isn't that people make a living out of relief care."
Ms Holden argued that the work was often done by friends or family, and so a subsidy was appropriate.
She said that meant the work was "informal", rather than carried out by people "engaged" as employees.
The case would set a precedent for the approximately 30,000 people who work as respite carers.
The Supreme Court Justices have yet to deliver their decision.