Under New Zealand law (section 106 of the Sentencing Act), a discharge without conviction can be made in any case where there’s no minimum penalty and where the judge feels that it’s valid. Cases where it might be are those where the direct or indirect results of the conviction would be out of proportion with the crime – for example if a lawyer were convicted of a minor charge, it might ruin their career, no matter how minor the direct penalty. That would therefore be a disprortionate outcome. Lawyers might not be the most sympathetic example, but discharges without conviction are used reasonably often, and most often reasonably. The courts can also impose other conditions, such as payment of reparations, or for Paki, treatment for alcohol abuse.
In this case, Paki was discharged because, as a son of the king, a conviction would preclude him from ever taking the crown. This case will undoubtedly garner significant public interest, but it may say more about people’s attitudes toward monarchy than it does about the law. The principles of equality before the law and judicial discretion will often clash, but add to the mix a birth right exemption and things become increasingly messy.