Taipu Moana, 59, was discharged without conviction after being found guilty of refusing a blood alcohol test in Huntly.

A drug and alcohol abuse counsellor has been discharged without conviction after refusing a blood alcohol test because he was sad.

Justice Ailsa Duffy said in a report on the High Court decision that Taipu Eric Moana was "emotionally vulnerable" after attending a tangi the day of the incident.

Her report said the tangi and death would have brought back memories of his sister, who died around six months earlier. It said "Moana may well have been feeling sad and emotionally vulnerable and this may have affected his decision-making on that day".

Moana was convicted of refusing a blood alcohol test in Huntly in March 2015, when he attempted to drive home after he consumed around five handles of beer.

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He picked leaves off a tree and proceeded to eat the leaves in a bid to avoid the police blood test.

In the Waikato District Court, he was fined $450 and disqualified from holding or obtaining a driver's licence for six months.

When Moana, 59, initially applied for discharge without conviction it was declined. He appealed the decision and on December 21, 2016, the High Court of New Zealand ruled Moana be discharged without conviction.

Its report into the decision was released on Monday.

The High Court report by Justice Duffy discussed the reasons why the conviction was overturned.

On the same day he was stopped, Moana had attended the tangi of a Huntly kaumatua.

This was six months after the death of a sister he was particularly close to. The High Court felt he had not sufficiently dealt with her death, instead trying to busy himself more than usual in order to avoid processing his feelings about her death.

The justices felt the conviction would impact his ability to continue practising in the alcohol and drug counselling area and it would be difficult for him to find further employment.

They noted when the district court judge refused the discharge without conviction, he believed Moana would not lose his job with Hauora Waikato Nga Ringa Awhina, where he worked as a senior alcohol drug counsellor.

But he did lose his job.

Moana now has part-time work as a cultural adviser at the Te Runanga o Kirikiriroa. The new role does not have a clinical component.

He has self-referred to Pai Ake Solutions Ltd and attended a number of interviews and counselling sessions.

The High Court report said the incident occurred during a "unique set of circumstances" that made Moana particularly vulnerable which may have affected his judgment. It said the offending was at the low end of the scale for the offence committed and Moana had an unblemished record of good behaviour.

A conviction would not only deprive him of a worthwhile role in his life, but deprive others of the many benefits that he could give to them in that role.

Because the original trial was before a judge only, the appeal process was to the High Court.