This week the High Court at Wellington has been hearing a challenge to the lawfulness of the police's conduct in procuring a search warrant and then conducting a search of Nicky Hager's house.
The allegation (as yet unproven) is that police misled the judge who issued the warrant, breached Hager's rights during the search, and then breached undertakings about what they would do with any items seized during the search.
The outcome is still to be determined, but it seems to be the latest example in a rising tide of cases in which the police and Crown prosecutors have been challenged in respect of the execution of search warrants and the conduct of criminal investigations and prosecutions.
Other high-profile examples include the Red Devils case in Nelson, the John Banks case and the Kim Dotcom raid. In each of those cases, the courts have been critical of the conduct of police or prosecutors, to varying extents.
It wasn't supposed to be this way. The Law Commission conducted a lengthy review of New Zealand's search and seizure laws, resulting in the Search and Seizure Act 2012 which was intended to clarify and modernise the law. But the problems suggest this hasn't helped, and there is an impression at least, including among lawyers, that too often when police or prosecutorial conduct is put under really close scrutiny by the courts it falls short.
Of course, that impression could be completely misleading - these are only a few very high-profile cases and they may be completely unrepresentative of what is happening in the run of ordinary cases.
But by the same token, most cases never get that kind of scrutiny in the first place. Not many people can afford to mount the sort of challenge that Dotcom, Banks and now Hager have made. So we don't know whether these cases are just outliers, or signs of a much larger problem.
Should we be concerned about this? Perhaps we should. There is a very strong public interest in ensuring that the state has the power and resources to investigate the commission of criminal offences.
But the police and Crown prosecutors have to wear two hats - they are also charged with defending the fundamental rights and freedoms of the public. Are they doing one of these jobs at the expense of the other?
The Attorney-General has announced that he has investigated the John Banks case and is satisfied with Crown Law's conduct. In his media release he also stated his "full confidence" in the Solicitor-General.
This is of course welcome, but it is nevertheless unnerving, at least for lawyers, that we have reached a point where the Government feels the need to express public confidence in the Crown's most senior law officer. That ought to go without saying. The fact that it didn't is a worry.
The courts provide essential scrutiny of the cases that come before them, but too often their ability to do so depends on defendants having the resources to mount an effective challenge. And of course, that scrutiny always comes after the fact: it is an ambulance at the bottom of the cliff rather than a fence at the top.
Similarly we have an Independent Police Conduct Authority which provides an additional avenue for complaints to be considered. But these consider individual cases, and the real question now is whether that is enough.
Have we reached a point where problems have become systemic, such that a far wider inquiry should be held? An inquiry could help reassure the public that there is no fundamental problem with our criminal justice system.
And if it identifies problems either with the law, or the interpretation and implementation of the law by the police and other authorities, then that would also be a very good outcome.
Ultimately it helps no one if the police cannot effectively investigate and prosecute criminal offences.
When prosecutions fail because of errors in the course of an investigation, there can be an enormous waste of time and resources, not to mention the distress caused to those affected - particularly the victims of crimes. In other words, the stakes are very high, and it is important that public confidence in our criminal justice system is not undermined.
An inquiry could help achieve that.
Nick Russell is a partner at Chen Palmer, public and employment law specialists.