A Kiwi mum who continually relives the moment her son was killed in a crash by a drug-affected driver says she cannot support legalising cannabis.
"Ask any parent who has lost a child to a cannabis-impaired driver if they would agree to it being legalised," Barbara Semb said in a recent letter to the editor published in the Herald.
Her son, Chris Semb, died aged 51 in Queensland, Australia, in 2014 when an oncoming van crossed the centreline near Bundaberg and hit his motorbike.
He was thrown up to 60m down the road by the force of the collision.
"Chris was riding along minding his own business, there had been traffic following him, he did absolutely nothing wrong, and then this van came on the wrong side of the road," Semb said.
"I see it in my head, I'm reliving it all the time."
The 31-year-old van driver, Hew Lewis, was found to be high on cannabis and a cocktail of prescription drugs and was sentenced to five years' jail.
Semb's comments come as the Government is preparing a draft bill outlining what rules will be used to manage cannabis use if it is legalised.
That will then be put to a referendum vote at next year's general election.
Opinion polls have mostly shown Kiwis support legalising cannabis, although a 1News Colmar Brunton Poll this month showed 52 per cent of people opposed its legalisation and only 39 per cent supported it.
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An independent economic analysis commissioned by the NZ Drug Foundation last year found that a legal, regulated market for the purchase of cannabis would bring between $185 million and $240m in new tax revenue, and that putting $150m a year back into health services would see wider societal benefits equating to about $225m a year.
Lawyers prosecuting Lewis in 2016 said his decision to take marijuana before getting behind the wheel had "the direct consequence" of taking another life, local media reported.
His defence lawyer also admitted Lewis' driving ability had been impaired by the amount of marijuana in his blood and that he had battled drug addiction since being exposed to cannabis as a child.
Semb feared legalising cannabis would lead to more people using the drug and driving while high.
She doubted the law would be enough to deter them from driving while impaired.
Just one tragic death had countless ramifications, she said.
Her son had worked as a fitter turner on mining equipment in Queensland and travelled back and forth to his family in Kerikeri.
Semb's painful memories resurface every time she visits Auckland Airport's international gate because that is where she hugged her son goodbye, weeks before he died.
"That's the last time I saw him, going through that gate. And I have to go through there every time I fly - I can't escape it," she said.
"There's things like that that people wouldn't even think about."
She also can't help picturing and reliving the crash when she gets behind the wheel of her own campervan.
Chris Semb's sister Ellen also expressed concern that more people would drive high if cannabis could be bought legally.
"I don't mind if people choose to have a glass of wine or smoke a joint in their own time, I just don't know how they are going to be able to police it," she said.
At present police must suspect a driver is impaired by drugs before asking them to take an impairment test.
If the driver performs badly in the test, police can stop them from driving and order them to take a blood test, looking for the presence of illegal and prescription drugs.
Drug Foundation executive director Ross Bell said drug-impaired driving was already a problem, regardless of the legal status.
Better education was needed to stop impaired drivers getting behind the wheel.
"The government is currently consulting on whether they should introduce roadside saliva drug screening tests and we think that there's merit in that."
"There is a bigger reason why you want to regulate cannabis and while there are some issues like on the road, we have to mitigate against those as well as address the main reason why we're trying to regulate cannabis."
The debate comes one month after the Government released details about next year's referendum.
There will be a simple Yes/No question at the referendum, asking voters to either favour the regulatory regime outlined in the draft bill or the status quo.
Details already released of what will be in the bill include:
• Allowing products to be bought only in a licensed premise from a licensed and registered retailer, and banning online or remote sales
• A ban on using cannabis publicly, allowing it only in a special licensed premise or on private property
• Controls on the potency of cannabis
• A legal purchase age of 20
• A ban on advertising of cannabis products, and requiring products to carry health information
• A state licensing regime to control the supply chain and the manufacture of all products, such as resins and edibles
• A ban on all imports of cannabis unless through a state-licensed wholesaler
Whether the vote will be binding has been questioned, because the Government could choose to ignore the referendum results, or change the bill after the vote.