The outcome of the case could have "huge ramifications" on the aged care industry, potentially costing it hundreds of millions of dollars if the union succeeds in this action, Mr Taylor said.
"Discrimination does not exist in aged residential care on the basis of gender, but I can say categorically that discrimination does exist in the health sector based on whether you are a private sector caregiver or a public sector caregiver.
"It's well known DHBs are funded to pay their caregivers at around $18 per hour while our funding only supports an average wage of around $15 per hour."
Successive governments had paid caregivers in DHB-owned and operated hospitals and aged-care facilities at a higher level than they funded private providers, Mr Taylor said.
"That's where the discrimination lies and it's at the heart of disparities between those caregivers employed in the public sector and those in the private sector. That's why our association has been advocating for pay equity since 2005."
TerraNova Homes and Care Ltd worked no differently to most other aged-care providers and paid about the industry average of just under $15 per hour, and had a pay scale based on performance and training, he said.
"We believe this case will prove TerraNova has not discriminated on the basis of gender, but rather that private aged-care providers need increased government funding so that caregivers can be paid the same rate as those employed in DHB facilities."