In late 2007, it was reported that O'Neill's cases took up 57 per cent of the Human Rights Tribunal's entire active caseload. He has since been barred from taking another case to that tribunal after lodging more than 100 complaints.
In the latest case he took court action against the New Zealand Law Society, which had chosen not to act on complaints about his lawyers when he was charged with offences under the Harassment Act.
By this month, the case had gone as far as the Court of Appeal, which noted that O'Neill's language in pursuing it "at times was abusive and, in some respects, scandalous".
The High Court had already struck the matter out, saying that O'Neill's statement of claim was a flagrant abuse of process and had no legal basis.
The newly-released Appeal Court decision also declined to take the matter any further.
It detailed a minute written by High Court Justice Francis Cooke, which noted that Justice Cooke was concerned by O'Neill's highly abusive communications and apparent threats of violence.
In February 2021, O'Neill sent a communication to the court describing one judge as a "lazy cow" and describing two others as perverts.
He said that the Law Society's counsel were not legitimate and that if they were not replaced, "choose your weapons (so) that we sought (sic) matter via the duel now that the court just can't be arsed to do justice any more, and we must now revert to violence to settle our affairs".
In other communications, O'Neill said court staff were "bent scum".
He said one staff member was a "recidivist pervert who will stop at nothing to get his leg over his female co-workers".
He demanded that another female staff member be turned out onto the streets where she could follow "her true calling of whore".
Justice Cooke said court staff – one of whom had been called a "gayboy" - and counsel need not engage with a litigant who used the court processes to abuse people.
The Appeal Court panel of Justices Miller, Brewer and Moore, said they asked O'Neil about his abuse of court staff.
He replied that those were his opinions and he had an absolute right to express them under the New Zealand Bill of Rights Act 1990.
"He is wrong about that. All rights are subject to reasonable limits prescribed by law," the judges said.
"Of the description of judges as perverts, he said that what he meant was that they had perverted the course of justice. We do not believe him and we think no reasonable observer could read his use of the term in that way.
"Of (Justice Cooke's) observation that he had threatened violence, he claimed that his language was obviously a joke. We do not believe that either."
The Justices asked if O'Neill was prepared to change his behaviour.
He told them he will not stop, and that as far as he was concerned what he said was true, he was justified in saying it, and the law recognised no limits to his rights.
In turning down leave to appeal to their court, the justices directed the registrar to refer their judgment to the Solicitor-General.
They said they wanted the Solicitor-General to consider further steps under Section 166 of the Senior Courts Act, which places limitations on people filing proceedings.
