Crimes Act 1962, s59(4) (4) To avoid doubt, it is affirmed that the Police have the discretion not to prosecute complaints against a parent of a child or person in the place of a parent of a child in relation to an offence involving the use of force against a child, where the offence is considered to be so inconsequential that there is no public interest in proceeding with a prosecution.However, I think that many people misunderstand the effect of this clause. There seems to be frequent reference to the interpretation of this clause needing to be addressed by the courts. But, in my view, is extremely doubtful that the courts will touch the clause: 1. The clause does not circumscribe illegal action. Subsection (1) provides the only legislative limit on criminal liability for assaulting children. Most people seem to accept that. 2. The clause only *affirms* prosecutorial discretion. The discretion is, of course, a discretion. That means it's for the Police to decide whether or not to prosecute. They might. They might not. On the one hand, it means they do not need to if the use of force is inconsequential. On the other hand, they might decide to prosecute even if it is inconsequential. Or, indeed, they might decide not to prosecute for other reasons. Notably, the Police are not legally prevented from prosecuting cases where the use of force is inconsequential. 3. Even if clause limited the exercise of discretion, or there was any other purported error or defect in the exercise of discretion, the courts generally do not review the exercise of discretion; that is, prosecutorial discretion is non-justiciable (not suitable to being checked or regulated by the courts). A useful statement of this principle is in the Court of Appeal's decision in Fox v Attorney-General  3 NZLR 62:
The constitutional position  In our system of government, the discretion to prosecute on behalf of the state and to determine the particular charges a defendant is to face is part of the function of Executive Government rather than the Courts. That allocation of the function recognises the governmental interest in seeing that justice is done and community expectations that criminal offenders are brought to justice are met.  There are various mechanisms for the accountability of those making prosecutorial decisions within structures of government and as part of the government’s own responsibility to the House of Representatives. These apply whether prosecution decisions are taken by law enforcement agencies such as the police, the Serious Fraud Office, or other government departments or public agencies, or by the Law Officers of the Crown, the Attorney-General and Solicitor-General, who have an overall responsibility for prosecution processes. The Attorney-General is, as well as being the senior Law Officer, the Minister directly responsible for the conduct of prosecutions laid indictably, once they have reached the stage of committal for trial following depositions. Other Ministers are likewise responsible to Parliament for conduct of particular prosecutions by the departments for which they are responsible. In all cases independence from political direction of prosecutorial decision making is an established constitutional practice in New Zealand. It is often reflected explicitly or implicitly in the legislative framework governing such departments and other public bodies and public officials. It is especially reflected in the role of the Solicitor-General in the prosecution process in New Zealand (J Ll J Edwards, The Attorney-General, Politics and the Public Interest (1984), pp 391 – 396; Joseph, Constitutional and Administrative Law in New Zealand (2nd ed), paras 9.5(3) and 25.8.2; Huscroft, The Attorney-General, the Bill of Rights and the Public Interest, in Huscroft and Rishworth, Rights & Freedoms (1995), p 135).  A decision by a public official to prosecute in any case involves the exercise of a discretionary public power. There are prosecution guidelines issued by the Solicitor-General which discuss that discretion and indicate how it is to be exercised. The current Prosecution Guidelines are reproduced in Criminal Prosecution (New Zealand Law Commission Preliminary Paper 28 (1997), Appendix B). When considering whether to prosecute, para 3 of the Law Commission paper states “there are two major factors to be considered: evidential sufficiency and the public interest”. The latter aspect requires consideration of “whether, given that an evidential basis for the prosecution exists, the public interest requires the prosecution to proceed” (para 3.3.1).  The Courts traditionally have been reluctant to interfere with decisions to initiate and continue prosecutions. In part this is because of the high content of judgment and discretion in the decisions that must be reached. But perhaps even more so it also reflects constitutional sensitivities in light of the Court’s own function of responsibility for conduct of criminal trials. This reluctance to interfere on the ground that the prosecution is thought to be inappropriate is widely apparent in the common law jurisdictions (see R v Humphrys  AC 1 at p 46 per Lord Salmon; Barton v R (1980) 147 CLR 75 at pp 94 – 95 per Gibbs CJ and Mason J; R v Jewitt  2 SCR 128 at para 25 per Dickson CJC; and R v Power (1994) 89 CCC (3d) 1 at pp 13 – 20 per L’Heureux-Dubé J delivering the majority judgment of the Supreme Court of Canada).The High Court in Polynesian Spa Ltd v Osborne  NZAR 408 was reluctant to rule that prosecutorial discretion could never be reviewed but accepted that the substantial policy and constitutional reasons against interference meant that "it will only be in rare cases" (namely, "if it were established that the prosecuting authority acted in bad faith or brought the prosecution for collateral purposes"). 4. The upshot of this orthodox principle is that the courts are unlikely to review the exercise of discretion or the meaning of subsection (4), either directly by judicial review or collaterally in the context of a criminal prosecution (except in cases of bad faith - an extremely high threshold). 5. The one complication is whether the affirmation of the prosecutorial discretion in legislation alters the present position. I've chatted with a few colleagues about this, and we've come to the view that it's unlikely that this changes things; fundamentally, the policy and constitutional concerns still remain and the legislative reference simply recognises the discretion (ie, it does not in itself confer the discretion). 6. That does not mean that the courts are powerless to respond to trivial charges. There is some ability to control prosecutions under the courts' powers to control abuse (but that's more likely were there is simply no evidence supporting the charges or use of prosecution for ulterior purposes). And, of course, the courts can address the matter after conviction, through their powers to discharge a defendant without conviction. But the central point remains, as a matter of law, the manner in which the prosecutorial discretion is exercised is essentially irrelevant in the eyes of the court.