Intellectual disabilities support organisation IHC will give evidence on behalf of the man, who died in 2006, as the Abuse in Care Royal Commission of Inquiry continues this week.
The commission is investigating abuse in state and faith-based care between 1950 and 1999, and is now hearing survivors share their experiences in seeking redress, such as compensation, counselling or an apology.
IHC director of advocacy Trish Grant will give evidence on Monday that the boy, known as "M", received no schooling, no pay for the work he did, and state authorities frustrated his attempts to have his abuse investigated.
M was born in 1928, and aged 6 was diagnosed as intellectually disabled, or as having "low intelligence", and sent to the Templeton Centre near Christchurch.
The recorded evidence for the diagnosis of low intelligence was that at six years old he did not know his surname, could not add two plus two and could not spell the word cat.
He was promised an education there, which he was desperately seeking, but was instead put to work.
Over the next 13 years there he was also physically and sexually abused.
In the 1990s he sought an apology from the Crown for the abuse and neglect he experienced in institutions.
It was not until 2003 that he got a financial settlement and an apology. He died in 2006, aged 78.
"Before IHC became involved in the development of the civil claim, M had tried unsuccessfully for years to have government investigate the abuse and neglect he experienced in an institution, the life opportunities he had missed, and provide him compensation," Grant said.
M's evidence is part of a broader claim, also detailing IHC's experiences of seeking justice on behalf of disabled children unlawfully discriminated against at school.
The discrimination case concerns a complaint lodged by IHC with the Human Rights Commission in 2008.
The case alleges that students with disabilities are denied the right to education and experience diverse traumas that result in poor life outcomes.
IHC has taken the case on behalf the 84,000 to 106,000 children in state schools who have disabilities and need accommodations to learn.
This complaint was finally given a preliminary hearing at the Human Rights Review Tribunal in 2015. IHC is yet to hear the outcome.
Disabled students continue to experience discrimination at school in 2020, Grant said.
"The students who gave evidence in 2008 have now left school and this unfair treatment has impacted on their adult lives."
IHC's complaint, lodged under the Human Rights Act, asked the Human Rights Commission to consider whether the policies and practices of the Ministry of Education constituted unlawful discrimination against students with disabilities.
"The time it has taken to progress the complaint and the obstructive and at times inappropriate way in which the human rights bodies and the Crown responded to IHC's case has meant that students with disabilities have not been able to access justice and have their voices heard."
