The inquiry involving a Supreme Court judge has parallels with a case concerning former Chilean dictator Augusto Pinochet, writes Richard Cornes.
The complaint of misconduct lodged against Supreme Court Justice Bill Wilson, by former senior judge Sir Edmund Thomas (though he is not the sole complainant) tests two new institutions early in their existence - the court itself, and the Office of the Judicial Conduct Commissioner.
Critics of the Labour Government's decision to end appeals to the Privy Council have already used the Saxmere saga and Justice Wilson's central role in it as evidence that New Zealand should not have ended the avenue of an appeal to the London-based Court. They are wrong.
The Supreme Court was able to deal with Saxmere's denial of a proper hearing before the Court of Appeal - as Phil Taylor reported in the Weekend Herald - with more dispatch, and at less cost to the parties, than the Privy Council.
Examples of embarrassments of varying degrees of seriousness involving top court judges, in some cases leading to resignation, can be found in a number of other countries, though they are not frequent.
For those with nostalgia for the Privy Council, recall the disrepute one of its judges - Lord Hoffmann - brought the Appellate Committee of the House of Lords (where Privy Council judges spend most of their time) into.
On October 17, 1998, Britain woke to the news that former military dictator General Augusto Pinochet of Chile had been arrested in a London private hospital.
The arrest was connected to an attempt to extradite Pinochet to Spain to answer charges that he had been responsible for the torture and murder of Spanish citizens living in Chile.
The case raised complex legal questions concerning the immunity of former Heads of State for acts committed during their time in power.
In the Appellate Committee Lord Hoffmann cast the deciding vote. The extradition process could continue.
After the decision Pinochet's lawyers realised that Lord Hoffmann was a director of Amnesty International Ltd, a fund-raising outfit for Amnesty International. Amnesty International had taken part in the case as an interested party, arguing against Pinochet.
In a move similar to the New Zealand Supreme Court's in the Saxmere litigation the Appellate Committee re-opened the matter, set aside its first decision and ordered the case be heard again before a new committee.
The new committee still found against Pinochet, but on much narrower grounds.
The case was hugely embarrassing and for a time it was thought Lord Hoffmann might resign. He did not.
The Appellate Committee recovered.
The Pinochet example is close to the Saxmere saga, but there is a difference.
This difference arises from a consideration of Justice Wilson's conduct throughout the Court of Appeal and two subsequent Supreme Court cases.
It is this conduct that has led to the extraordinary circumstance of a complaint being laid against a serving judge of the Supreme Court by a former member of the court itself.
Principles of natural justice, and the statute which establishes the Office of Judicial Conduct Commissioner, require that Justice Wilson must be given proper opportunity to answer the allegations of misconduct.
The constitutional imperative of judicial independence requires that no judge should be hounded from their court on the basis of media pressure.
Judges are extraordinarily difficult to remove once appointed. This protection is not for them, it is for us.
As New Zealanders we depend on the existence of an independent and impartial judiciary to decide disputes between us, and to stand between us and the state.
An independent judiciary is one of the things that ensures our freedom - judges decide according to law, not according to who has more power.
With the protection judges enjoy from being easily fired come obligations.
One of these must be to maintain the integrity of the judicial branch, to observe the judicial oath and to act at all times consistently with the values of judicial office, to take care that their actions do not bring the judicial branch, or the court they serve on, into disrepute.
In the first Supreme Court Saxmere decision Justice Wilson comes in for some uncomfortable criticism from his colleagues.
Part of that criticism includes an admonishment to judges in Justice Wilson's position to make full and prompt disclosure of relevant facts in such cases - not to put lawyers before them in the embarrassing position of having to keep going back to the judge to seek further clarification.
Yet in the second Saxmere decision it is apparent that Justice Wilson, though having the benefit of the first decision, did not immediately make full disclosure.
The full picture emerged in further instalments - the last of which was "at the invitation of the court".
Is this a matter of mere embarrassment, or an aspect of misconduct which could lead to Justice Wilson's resignation or removal?
Since Saturday, New Zealanders know that one former senior judge - Sir Edmund Thomas - would have serious reservations about sitting with Justice Wilson.
Much now rests on the credibility of Sir David Gascoigne's (the Judicial Conduct Commissioner) determination as to whether to dismiss the complaints (he would have to provide the complainants with his reasons for doing so), or allow them to proceed for further investigation.
* Richard Cornes is a senior lecturer in law at Essex University and a barrister and solicitor of the New Zealand High Court. His course "Understanding Judges" ran in the 2010 University of Otago Summer School.