Richard Moananu, then 31, was jailed in November 2020 for 15 years with a non-parole period of 10 years over the Sydney crash.
But in a majority decision on Friday, the NSW Court of Criminal Appeal quashed the term and re-sentenced him to 12-and-a-half years with a non-parole period of eight years and four months.
He had pleaded guilty to two counts of manslaughter and one count of aggravated driving causing grievous bodily harm, asking the District Court judge to also take into account other offences.
Bronko Hoang, the sole survivor of the September 2017 collision, sustained life-altering injuries to his body and brain, and profound psychological trauma.
His wife Katherine and a 17-year-old learner driver died when Moananu's car ploughed into theirs in Orchard Hills, western Sydney.
His twins were due to be born the following week.
When Mr Hoang awoke from a coma in hospital, he said the nurses had to "tie him down" as they continually reminded him of what happened.
Justices Mark Leeming and Peter Hamill, with Justice Derek Price dissenting, concluded the sentence was "manifestly excessive".
"The course of conduct undertaken by the applicant in the present case was outrageous and appalling," Justice Hamill said.
"It threatened the lives of many road users and had a devastating impact on Mr Hoang and his family.
"The tragedy to that family is barely able to be imagined.
"On the other hand, the applicant presented a strong subjective case, demonstrated deep remorse from the day of the collision and received a 25 per cent discount for his early plea of guilty."
When compared with sentences imposed in similar cases, he found the starting points for the judge's sentences were "very high".
"Assuming those sentences were within a legitimate discretionary range, they stretched that range to its limit
"When the degree of notional accumulation is taken into account, and comparison is made to other cases, I am persuaded that the aggregate sentence imposed on the applicant was manifestly excessive."
But Justice Price said the extent of notional accumulation did not lead to a conclusion that the aggregate sentence is unreasonable or plainly unjust.
"The destruction of the lives and future aspirations of the innocent victims in the car being driven by (the teenager) was brought about by the applicant's appalling conduct," he said.
The sentence imposed had reflected the totality of his criminality, he concluded.
Moananu had been speeding with four times the legal limit of alcohol in his system, which the sentencing judge said showed a total disregard for all road users that day.
He was driving on an expired licence when he veered onto the wrong side of the road, travelling more than 45km/h over the speed limit.
Witnesses saw Moananu's car weave in and out of traffic, fail to indicate properly, run a red light and drive over a grassy median strip before it became airborne.
10°C