Beverley Aldridge from advocacy group Otamatea Grey Power has appeared before MPs and argued for medicinal cannabis to be legalised.
Ms Aldridge told Newshub: "It would seem, if we're the third highest country in the world of people who actually take cannabis or admit taking it, there probably are a lot of people who are not admitting to taking it, then it would seem that only groups like us are being denied it.
"It's freely available to everybody except us and we feel we have a right to have it for our health benefits. We don't want to be on pharmaceutical drugs.
"Many countries around the world have given access to it and they trust their citizenry to be responsible with it."
Ms Aldridge, who made a presentation to a select committee on Thursday, says she has has never smoked cannabis, but has been researching it with other members of her local Grey Power association.
"We can include the cannabis plant in our smoothies and our juices", Ms Aldridge says.
She wants to use it for health purposes, and to prevent further illness. She is also a naturopath.
"We've done so much research, the research is online, to tell us what the benefits are".
Ms Aldridge attended the select committee with her husband and her son, and told MPs that cannabis should be legalised.
"Cannabis prohibition plays an enormous part in perpetuating our prison industry".
"Prohibition of cannabis is not a war against drugs it is a war of a government against his people.
"We have a moral obligation to do something about it".
Grey Power New Zealand was formed in February 1986 to protest proposed changes to Superannuation.
They have associations throughout the country and say they have up to 90,000 financial members.
Grey Power's national president Tom O'Connor has previously distanced the national group from the campaign to legalise medical marijuana.
"We don't have a formal policy on the legalisation of marijuana and we are probably unlikely to anytime soon. The reality is that we don't know enough about the substance."
He said there was a growing trend for activists and single issue groups to attempt to use the Grey Power brand to promote their causes.
"We get all sorts of weird and wonderful ideas popping up from time to time but we are very careful about who and what we support nationally."