For the first time yesterday, the details of Ericksen's drug use were revealed. She admitted ingesting methamphetamine on the morning of July 8 - about 24 hours before the fatal crash.
Both the Crown and defence agreed that there was no scientific way of proving the effect that drug use had on Ericksen's driving, but neither argued that it was not a contributing factor in the crash.
She began drug counselling just seven weeks ago, and her lawyer Peter Kaye said it was unclear whether she had stopped using methamphetamine completely.
"It would be too much to expect her to say 'I've stopped taking methamphetamine'.
"It's a progressive path she's started," he told Judge Roy Wade at the hearing in the Auckland District Court.
Crown Prosecutor Emma Finlayson-Davis said a report from a social worker showed Ericksen had refused to be tested for methamphetamine use before sentencing.
"The social worker was unable to satisfy herself as to whether (Ericksen) was continuing to use drugs. Certainly that raises some concerns ... demonstrates her use being a problem."
It was also revealed in court that three of the four tyres on Ericksen's car were unsafe, which contributed to the crash. She had acquired the car just two weeks earlier and it had a Warrant of Fitness. However, the tyres would not have passed the next check, police reported.
Mr Kaye pleaded with Judge Wade for a lenient sentence. He said Ericksen was a solo mother to Gemma, who relied on her heavily. Jailing her would effectively cause irreparable suffering to the little girl.
"She went through this accident as well. She herself was hurt, and hurt badly. She woke up in hospital with recurring nightmares, which she's still having. Gemma ... is having trouble and needs to sleep with her mother.
"The difficulty is, if (Ericksen) were to go to prison, not only would she suffer but Gemma would suffer as well."
Mr Kaye said Bryer's death was a "complete accident" and Ericksen expressed "genuine remorse".
Judge Wade said sentencing Ericksen was difficult.
"I came into court this morning convinced that I would have to send you to prison.
"But, I've been persuaded to change my mind.
"Nothing less than the maximum term of home detention would suffice," he said.
He said regardless of whether Ericksen's drug use caused the crash, he needed to condemn her actions. He was also clear that the state of her tyres was unacceptable.
"You will go to your grave knowing in your conscience that you are responsible for the death of one of your children, and the serious injuries suffered by another.
"I am satisfied that if I were to send you to prison, the effect on Gemma would be appalling.
"For those reasons, and not without substantial hesitation, I am sentencing you to the maximum 12 months' home detention," he said.
Judge Wade also ordered Ericksen to undergo any drug treatment prescribed by Probation Services, and disqualified her from driving for four years from the end of her sentence.
Sensible Sentencing Trust spokeswoman Ruth Money said it beggared belief that Ericksen had sought drug counselling just seven weeks ago, given the accident occurred more than a year ago. Similarly, the refusal to submit to a drug test rankled.
It was clear Ericksen had been saved by her remaining daughter's needs and that Judge Wade's hands were tied in this case in relation to imposing a jail term, Ms Money said.
"It's a sad indictment on society that this wee girl, there's nowhere that she can go to be safe and so we leave her with a mother who is refusing a drug test even after she's killed the little girl's elder sister. It makes me feel ill."
"The only reason she is not in prison is for that little girl."
Meth effect hard to measure: lawyer
A blood sample taken from Toni Ericksen after she crashed her car, killing her 12-year-old daughter, showed she had 0.6 milligrams of methamphetamine per litre of blood in her system.
However, there was no way of proving how soon before the crash she ingested it, how much she took and what effect, if any, it had on her driving.
Crown Prosecutor Emma Finlayson-Davis said unlike the tests for drivers who crashed after drinking alcohol, there was no scientific equivalent for "quantifying or isolating" the effect of methamphetamine.
However, the fact that it was in her system when she was operating a vehicle was, by law, enough to prosecute her.
"You can certainly infer that it played a part," she said in relation to Ericksen's drug use.
"The blood reading itself doesn't tell us particularly much ... (but) she had methamphetamine in her system at the relevant time."
Judge Roy Wade said Ericksen's behaviour after the crash was such that police considered she was affected by methamphetamine.
She abused police and ambulance officers trying to treat her children and was aggressive. He said the reaction could have been shock, but the first officer on the scene recognised a clear sign of drug use.
