Seven people died in the crash.
The horror road crash at Waverley that killed seven people could have been prevented if someone had reported the culprit driver was high on drugs.
Two Hawera McDonald's restaurant staff who served the killer driver - and noted he was "way gone" 30 minutes before the crash - could have called police, says a coroner's report released today.
Jeremy Thompson had repeatedly consumed synthetic cannabis on the day of the crash on June 27 last year, so had his partner Ani Nohinohi, who was the sole survivor.
His car collided with an oncoming vehicle, killing seven people - Thompson, 28, his 6-month-old daughter Shady Thompson, and Nivek Madams, 8.
Four people also died in the car he struck: Ian Porteous, 80, his wife Rosalie, 76, his sister Ora Keene, 84, and friend Brenda Williams, 79.
A coroner's report released today said the crash happened because Thompson was driving while impaired by cannabis.
The family were on there way to Whanganui when they stopped in Hawera and continued smoking the drug.
Afterwards they went to the Hawera McDonald's and used the drive-thru to place an order.
The woman who served them said Thompson was slurring his words and was "already gone".
It was reported that she could smell cannabis, and witnessed Nohinohi packing something into a metal pipe in the vehicle.
As the family drove away, the McDonald's worker reported told her senior manager that Thompson and Nohinohi were "way gone".
Shortly after, while heading south on State Highway 3, Thompson lost control of the vehicle, crossed the centreline and collided with the other vehicle involved in the crash.
The coroner found that three people - Nohinohi and two McDonald's drive-thru restaurant staff - could have acted to stop Thompson continuing driving.
"Nohinohi knew that Thompson had smoked cannabis and so did the two McDonald's workers in Hawera. It is unfortunate that Nohinohi did not attempt to prevent Thompson from driving but her judgement was impaired - as well - by cannabis," Coroner Tim Scott said.
"It is also unfortunate that one or the other of the two McDonald's workers did not contact the Hawera Police ... it is possible, although there is no certainty about this, that had they done so, the police may have been able to stop Thompson and prevent him from driving further."
Coroner Scott said while it was not possible to establish with absolute certainty the factors that led Thompson to crash, the possibilities were fatigue, inattention, distraction or drug impairment.
"However, the overwhelming factor is that Thompson had consumed a very considerable amount of synthetic cannabis before and perhaps while driving," he said.
"If he fell asleep, that is probably why ... He was not fit to drive, and the result was the crash."
Thompson was also on his learner's licence and had more than 100 demerit points to his name.
Nohinohi told the inquest she had also consumed synthetic cannabis that day and could not remember the crash.
"I think it is quite likely that I had fallen asleep because I had been 'synnied out'," she said.
Nohinohi had told the coroner that she thought her partner was OK to drive because he had smoked synthetic cannabis before and then driven.
Nohinohi had synthetics in the car, but none was smoked because of the two children also inside the vehicle.
In a statement read to the court, she apologised to everyone affected by the crash.
"I'm very sorry about the tragic outcome for so many families and friends ... because of some poor choices, seven people lost their lives."
Wednesday would have been Nivek Madams' ninth birthday - but instead of a little girl's party full of laughter, kids' games and sparkly presents, her family decorated her grave with helium balloons and flowers.
Clark and Nivek's mother, Ani Nohinohi, gathered with extended family at the Whanganui cemetery to celebrate the 8-year-old's short life.
They marked the day with a unicorn party and remembered a bright young girl who was "funny, engaging and clever" and who had dreams of becoming a doctor.
The lives of Ian and Rosalie Porteous, Ora Keene, and Brenda Williams will also be marked at an event taking place at the Waverley Bowling Club tomorrow.
The four victims were all associated with the club and are said to have been a big part of the South Taranaki community.
At the Waverley Racing Club, members also marked the anniversary of the crash, which happened on the road outside the club's premises. The club had a race meet the day after the crash last year, and attendees were stunned as the horror of the accident became known.
This year's June race meet at the club fell on the same date as the anniversary of the crash.
Its jockeys wore black armbands to acknowledge the incident and observed a moment of silence. The race-day programme also made special mention to those lost in the incident.
Meanwhile, Nivek's former school, Stratford Primary, is taking time out of their day today to remember the former pupil.
Volunteers are visiting the school and will be working on the garden where there is a memorial for Nivek.
"A tree was planted last year following the crash and it's been pride and place for the Room 20 kids," deputy principal Aaron Moore said.
"The kids have some paintings that have been done to go on the fence nearby."
Questioned at the inquest by Logan Porteous - the son of crash victims Ian and Rosalie - made a point of stating that the police should be given more powers to randomly stop and check without cause for drug-impaired drivers.
"It's not our roads causing out road toll as much as the drivers," he said.
"We will as a family fight for this in the name of the innocent people who were killed in this accident, as a result of a driver under the influence of drugs."
Coroner Scott said he supported the opinion.
Nelson MP Nick Smith said the Government must act on the strong support for roadside drug testing after the findings of the Coroner's report.
"The coroner's findings must shake the Government out of its complacency over drug-impaired driving. The Coroner explicitly identifies cannabis as the cause of this horrific crash and adds to the groundswell of public support for random roadside drug testing," Smith said.
"The findings add weight to Matthew's Petition calling for the urgent introduction of random roadside drug testing. It was started by Karen Dow whose son Matthew was killed by a drugged-driver in Nelson. The families of the Waverley victims joined with Karen to push for change.
"Random roadside drug testing could have prevented this horrific Waverley crash and these seven tragic deaths."
Smith said the crash in June 2018 was particularly horrific, but every week people are being killed by drug-impaired drivers.
"Fatalities from crashes involving drug-impaired drivers have increased from 14 to more than 70 in the past four years.
"The anniversary of this horrific Waverley crash and this potent Coroner's report, the Government has no excuses for not getting on urgently with implementing roadside drug testing," he said.
The woman was shaken by the incident.