At least 100,000 New Zealand children and disabled adults were taken off their families and held in state institutions between the 1950s and 1990s. Successive reports have argued abuse was systemic during that time.
Martin, born in 1957, suffered a brain injury after his doctor used forceps at birth, and at 18 months of age was sent to the Kimberley Centre, a now-closed psychiatric hospital in Levin.
"A doctor told my mother I was mentally retarded," Martin told the inquiry.
"He told my mother to send me away and forget about me."
He wanted to be with his family, wanted to grow up with his sister, but he was not allowed to.
The experience at Kimberly was dehumanising, he said.
"I do not remember being picked up, or loved and cuddled ... we were just a number."
He was returned to his family for a brief period age 7, but his parents could not cope.
"I was told I was mentally handicapped, dumb, thick as a plank of wood and would always need other people to do things for me."
He was made a ward of the state and shifted through foster homes where abuse continued.
"I would get the jug cord, at night I was wetting the bed and to punish me they made me kneel on a wood pile for hours. That was torture."
He returned to Kimberly age 9, where he witnessed and experienced "shocking" abuse.
"These were people with the highest needs ... I did not understand how people could be so cruel.
"If someone had an accident and soiled themselves, they were just left in their dirty clothes.
"I saw this completely naked boy who had had an accident being hosed down by the staff using a fire hydrant hose.
"He would try to stand up and be knocked over again."
The first time he was sexually abused was by a male nurse at Kimberly.
"I was so young I did not know what was happening."
The children were not allowed to be individuals. They did not have normal childhoods, friends, even pets.
"We had to share a pool of clothes and grab what we could get. We never had our own underwear. They didn't let us just be a kid.
"We were colour coded in groups and had stars and labels and categories. We all had the same bowl haircuts on the same day."
He was deemed "too dumb" for secondary school, and after a stint at Lake Alice he was moved to Campbell Park, a school in North Dunedin
Almost immediately he was sexually abused again, by a group of older boys.
"It should never have been allowed to happen," Martin said.
"At that time of my life, I was displaying so many signs of abuse, but nobody picked up on these signs, or if they were they were ignored."
Instead, he was punished for playing up.
At 15 he was released from institutions, when he became aware of how little he knew of the outside world.
"I had to learn to survive and to live again. I realised I didn't know lots of things other New Zealanders did. It was like I wasn't even a citizen.
"I didn't know about the All Blacks ... but just like thousands of other boys, my greatest pleasure was kicking my rugby ball."
He recalled the protests against the Springbok tour in 1981, about the rights and freedoms of black people in South Africa.
"I remember feeling like I hardly had any human rights. Nobody was marching for me, or for anyone else with a disability."
The experiences in state care had a lifelong impact on him, he said.
In 2016 he became the first person with a learning disability to be elected onto a United Nations Treaty Body, the Committee for the Rights of Persons with Disabilities.
Martin said while those larger institutions had now closed, the smaller homes were made of the "same bricks and mortar".
He wanted to see New Zealand become more inclusive of people with disabilities, especially around decision-making and the right to choose where they lived and with whom.
"Still, no one is allowed to be an individual. But we are all unique, and all bring different things to the world we live in."
