Her parents asked for a coronial inquest after Miss O'Brien's former partner and father of their two children published on Facebook soon after the crash "May this be a massive wake up call to Everyone. Never txt and Drive".
His comments were widely reported in the media, including being part of a TV documentary on the dangers of texting and driving. Their two children Faith and Phoenix, now aged 5 and 6, were seriously injured in the crash and were now living with their father.
Mrs O'Brien said after the hearing that they wanted an inquest in order to put the record straight and were relieved by the coroner's comments.
"Tonight I will have a good sleep. We know she is cleared. It is finally over, we can get on with our lives now."
A police deposition read by crash analyst Senior Constable Tim Shields said the Te Puna crash was witnessed by a person in the vehicle travelling behind Miss O'Brien.
She first noticed the car when it started to make sudden movements, with the left tyre smoking. She then saw it do a small zig zag, like an over correction.
The driver then saw Miss O'Brien reach her left hand back into the back seat. The car then did another zig-zag and she saw Miss O'Brien put her hand back on to the wheel. Immediately the car crossed to the opposite side of the road and crashed into the car coming from the opposite direction.
Mr Shields said the borrowed car had a particularly poor rear tyre. One of the tyres was a small space-saver spare wheel that ran at higher pressures. He agreed that the state of the tyre could have had a significant effect.
He said Miss O'Brien's cellphone was found at the scene of the accident and opened to her messaging (text) application. While messages had been received, there were no times recorded. There was an unsent text on her phone.
He told Dr Bain that there was no way of knowing if the text was written prior to her getting into the car or after she was in the car.
Mr Shields said Mrs O'Brien had mentioned that her daughter constantly had a cellphone in her hand. She told police that she had snatched her phone off her a few times when her daughter was driving and texting or reading a text.
The day of the accident, Miss O'Brien had been at a night club until about 3am and was out of bed about 7am. Trace levels of alcohol were found in her blood and no drugs.
Mrs O'Brien told the court that her daughter and two children were on their way to a birthday party when the accident happened.
"She was happier than I had ever seen her."
Her grandson Phoenix had a party blower. She surmised that Phoenix may have dropped the party blower in the car and Tracey had reached back to pick it up.
Mrs O'Brien said there was no proof her daughter had been on the phone, only what her ex-partner had said.
Miss O'Brien's ex-partner Matt Ruddell told the Bay of Plenty Times afterwards that her phone could still have been a cause for the crash, but there was a lack of proof. He said he had advocated all along that the cause was driver distraction.
