A Canterbury father is calling for an overhaul of the way drivers are tested for illicit substances after learning of the horrific circumstances of his son's death.
For just over two years, Ron Crone has immersed himself in coroner's reports and crash statistics after his son Ethan died after crashing into a tree on his way to work early on May 30, 2017.
He lay there slowly dying for two minutes after being flung from the car. Because of heavy fog he was not discovered until two hours later.
Crone is speaking out to coincide with a new NZ Transport Agency road safety campaign dubbed @Unsaid kicking off tonight to raise awareness and harm caused by drug driving.
The campaign will be fronted by Wellington woman Ashleigh, whose cousin, Chris, died in a drug driving crash in New South Wales, Australia, in 2014.
Ashleigh will also encourage others to share their stories with her, and if so, with approval, she will then re-tell their stories on television each night at 6pm for the next six weeks.
An autopsy report revealed Ethan had cannabis in his system after smoking it the night before.
Ron Crone said drastic changes need to made as long as the normalisation of cannabis continued.
"He was a great lad ... but unfortunately he smoked cannabis and it affected his driving and perception in foggy conditions and he died accordingly; a horrible, painful death."
He said his son had smoked cannabis for a lot of his life, but he and new wife, Ruth, only found out when he was 17.
Ethan had been living with his mother, Natasha Richardson, at her Fernside, Christchurch, home and was on way to work when he missed the corner and crashed about 6.30am.
Ron Crone wants a zero limit placed on drug driving which he wanted police to be able to do randomly, like road side testing for alcohol. He also called for more testing in the work place.
However, Government discussion documents had revealed several difficulties in any possible law change including breaching people's rights under the Bill of Rights Act.
Data from NZTA shows the number of fatal crashes involving drugs peaked in 2017 at 88 deaths, when it surpassed the number of people - 74 - who died with a reading over the legal blood alcohol limit.
But Ethan's mother, Natasha Richardson, disputes cannabis was the cause of the crash.
She said it was a "super foggy" morning, there was no road sign indicating the almost 90 degree turn in the road and her son was likely not driving to the conditions.
"He obviously had a smoke the night before but that had nothing to do with his accident or why it happened.
"He was 24 years old. I'm not policing what he was doing. He wasn't doing it around us or around the kids and I do really believe that it was a just stupid mistake on the road not because he had cannabis in his system."
NZTA spokesman Andy Knackstedt said drug driving was "a difficult issue for New Zealanders to talk about".
"We know that drug driving is a big problem, we don't often hear directly from the people who are directly affected by it; people who have lost friends or family ... so this is really about giving a voice to those people and by extension raisin awareness of the issue further."
AA's Dylan Thomson said drug driving had been the country's "hidden killer" for a number of years as it was an issue that had flown under the radar due to the delay in waiting for toxicity results.
He expected the campaign to make a huge impact as it asked Kiwis to get involved to share their stories.
Caroline Perry, director of road safety charity Brake NZ, was concerned at the alarming increase in injuries and deaths caused by drug driving.
"Cannabis and methamphetamine are the main drugs detected in drug-impaired drivers, but there are also other drugs that affect driving, including some prescription medication.
"Some drivers also mix drugs and alcohol, which increases the risk of crashing even more. One study of fatal crashes in the US found drivers who have consumed both alcohol and illegal drugs are 23 times more likely to be involved in a fatal crash than a sober driver."
• People who want to share their stories can do so via @unsaid on Facebook or Instagram or by emailing: firstname.lastname@example.org