"Statistics and empirical data shows us that Māori are six times more likely to get arrested for marijuana then non-Māori and they are six times more likely to get a custodial or corrective sentence then non-Māori and are six times more likely to get a longer sentence then non-Māori.
"It's clogging up the justice system, clogging up police work, clogging up Corrections and prisons where police and other justice operations should be more targeted at deadly crime like methamphetamine, domestic violence and other such whānau oppressive activities."
Tomoana said the iwi had previously supported the growing of hemp for medicinal and nutritional purposes through Te Taiwhenua o Tāmaki-nui-ā-Rua who were "well down the track in their due diligence of this project".
He said they also had strong relationships with Massey University, other growers and Hemp Sun of China, one of the biggest producers of nutritional and medicinal products from the production of hemp.
"In the marijuana debate it has been established that it does have impacts and effects on health and we as Ngāti Kahungunu believe that this is a health issue not a criminal issue," he said.
"We also support the exploration and establishment of medical cannabis facilities within Ngāti Kahungunu as it has been proven world-wide that the beneficial health effects and impacts it has on individuals and families.
"We will explore the industrial production of medicinal cannabis to improve people's health and wellbeing."
He said the decision to support the legalisation of cannabis was not taken lightly.
"We do it to heighten the awareness of our people to other elements within our society, some of which are legal, that cause more damage to whānau than marijuana, including alcohol, nicotine and methamphetamine which have dire outcomes on the wellbeing of our whānau and mokopuna.
"Marijuana has been in our communities - Māori and non-Māori - for many years.
"These communities and the individuals within them continue to be gainfully employed and to be positive contributors to our communities."
He said the board urged everyone to think "very carefully" about whether they supported or did not support the Iwi's decision.
"The main thing is, to have your say, and we invite your critical support or otherwise and constructive criticism around our stance."
About the proposed Cannabis Legislation and Control Bill
The non-binding 2020 New Zealand cannabis referendum will be held on October 17 with the general election and a euthanasia referendum, on whether to legalise the sale, use, possession and production of cannabis.
The proposed Bill sets out a way for the Government to control and regulate cannabis. This regulatory model covers how people can produce, supply, or consume cannabis.
The Bill's main purpose is to reduce cannabis-related harm to individuals, families/whānau and communities.
If more than 50 per cent of people vote "Yes" in the referendum, recreational cannabis wouldn't become legal straight away.
The incoming Government can introduce a Bill to Parliament that would legalise and control cannabis. This process would include the opportunity for the public to share their thoughts and ideas on how the law might work.
If more than 50 per cent of people vote "No", recreational cannabis would remain illegal.
Medicinal cannabis and hemp will not be affected by the outcome of the referendum. Medicinal use of cannabis will still be allowed if prescribed by a doctor, and hemp will still be legal.