The consequences of a conviction, in particular to Moala's rugby career and future prospects, would be out of all proportion to the crime, he said.
Moala's lawyer, Paul Wicks, QC, says all judges followed the legal requirements to make such a decision, having looked at all the evidence before them.
However, the case has raised accusations that New Zealand courts have become a "two-tier system of justice", giving preferential treatment to celebrities.
University of Auckland law professor Bill Hodge says he is concerned by a run of cases involving athletes being discharged with conviction, on the basis it will affect their employment, their ability to travel, or compete in international competitions.
It seems like New Zealand is setting up a two-tier system of justice, where one class of people get one form of justice, and a different class of people get another, he says.
Cases such as this reinforce the view that people are treated differently when they appear before the courts depending on their public profile or their occupation.
Others, such as Tauranga lawyer Paul Mabey QC, see it differently. In a letter in today's edition, he argues anyone before the courts can apply for a discharge without conviction and this will be considered according to the facts. Judges, he says, are the ones to make these decisions and the professor's comments are not only wrong but risk undermining public confidence in the judiciary.
He makes a good point but this doesn't mean laypeople, or those in academia, cannot have opinions on this issue or disagree with a judge's decision.
In the Moala case, the consequences of conviction would have indeed been harsh for him. No doubt he was aware of the potential fallout of a conviction on his playing career before he got into a brawl at a bar. However, a conviction could also have an equally devastating impact on a tradesman wanting to ply his trade overseas.
There does need to be provision within the Sentencing Act for judges to use their discretion but this should be applied rarely and only in the most extreme circumstance. An example would be someone who is a leader in their field but unable to carry out critical public services because they had been convicted of a relatively minor offence.
But this did not apply in Moala's case.
There are plenty of talented rugby players who would be more than willing to take Moala's place and keep their nose clean for the privilege. Most players will no doubt be aware of the high level of scrutiny they are under given their public profiles.
Moala is not the first sportsman to be discharged without conviction and it's a fair bet he will not be the last. Nor is this controversy limited to cases involving sportspeople.
Last year an Air New Zealand pilot caught riding a scooter without a helmet and at more than two-and-a-half times the alcohol limit was also discharged without conviction.
In making that decision Judge Ajit Singh said a drink-driving conviction would stop Aucklander George Robert Meyer, 32, working as a long-haul pilot and granted his application for a discharge to maintain a clean record.
Decisions such as these open the justice system up to further criticism. There should not be separate laws for athletes or people with high-paying jobs.
