The link is here. Unfortunately, behind a paywall. From a practical standpoint, the mere appearance of impropriety should be enough to say this is unethical. I cannot imagine any person feeling they got a fair shake when the judge’s son represents the other side.
As a brief aside, ethics are often seen as synonymous with moral, but while they are related, they are not the same. One can be ethical and immoral, as well as moral and unethical depending on what moral precepts you hold dear. In some point in the future I might do a video on this.