Ian David Macnee (46) was jailed for eight months when he appeared in the Dunedin District Court in March on an aggravated charge of driving while impaired by drugs.
His counsel, Brendan Stephenson, argued in the High Court at Dunedin that the sentence was manifestly excessive.
He claimed Macnee should have received a combination of community detention, supervision and community work.
But Justice Cameron Mander, in a judgement released this week, said Judge Michael Crosbie had made no error.
Twice in the 1990s Macnee was convicted of drink-driving and in 2011 he was sentenced for cultivating, possessing and selling cannabis.
"While I accept that the break in Mr Macnee's offending can be interpreted as an indicator of progress and that his current offending could be viewed as something of a `slip-up', the nature of the offending and the risk of its repetition entitled the court to give weight to the need to protect the community and to take a stern and punitive approach, perhaps in the hope that by bringing home to Mr Macnee the seriousness of his actions, he might be motivated to take stronger rehabilitative steps to address his drug difficulties," Justice Mander said.
When Macnee got behind the wheel on October 21, he had consumed his prescription methadone and topped it up with cannabis and diazepam.
Driving south on State Highway 1 near Henley, he passed a car on a blind corner, causing an oncoming vehicle to take evasive action. Then, entering Waihola, the defendant wove wildly across both lanes of the highway.
A driver in front, seeing the danger, tried to slow Macnee down but he mounted the left-side footpath to get around them.
Before finally pulling over, he clipped a vehicle towing a trailer.
Macnee had to be assisted by members of the public to undo his seatbelt and leave the car.
The defendant wrote a letter saying he had no memory of the offending and was "extremely ashamed" and "truly sorry".
Mr Stephenson said the sentencing judge had incorrectly assessed his client's remorse and his efforts at rehabilitation.
Justice Mander, though, rejected that argument.
"Mr Macnee has not succeeded in controlling his addiction.
"To the contrary, his continued addiction had now resulted in near-fatal consequences for others, and, while it is not to be over-emphasised, his present offending does not appear to have been a watershed or turning point for him."
He had taken no new or more intensive steps to address his drug difficulties, the judge said.
"The court, therefore, is left with the significant risk that Mr Macnee presents to the public, without any real basis to believe there will not simply be a continuation of the status quo in terms of his rehabilitative efforts to prevent this type of offending."
Macnee was ordered to pay $750 reparation and banned from driving for two years.
