Helen Clark is throwing her weight behind cannabis legalisation because she says the drug's already widely available.

The Former Prime Minister told Kerre McIvor the referendum is a once in a generation opportunity to get this law right.

Clark says there is currently an illegal market where organised crime profit.

“It doesn't make sense to criminalise people who take this widely used drug. “

Helen Clark joined Kerre McIvor for an hour of talkback, taking listener's calls on their questions and concerns about the referendum'.

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