This chapter discusses defences, which are a fundamental part of criminal law, and reflect important limitations on the proper scope of punishable conduct. It is the purpose of this chapter to set out and critique the law relating to defences, in both treaty-based and customary international law. This chapter is concerned with substantive defences; it does not deal with issues such as immunity, youth, ne bis in idem, or limitation periods.

Of all the common law jurisdictions, New Zealand’s administrative law has probably stayed closest to that of England. Even so, notable differences have developed. The most distinctive part of the local law relates to the Treaty of Waitangi, and the extent to which it constrains the exercise of public powers. On issues common to both jurisdictions, there is a mix of more interventionist or liberal approaches and more conservative ones. A more interventionist approach is notable as regards the effect given to unincorporated international treaties. A more conservative approach can be observed to the human rights legislation and also still, at least to some extent, to the substantive grounds of judicial review (heightened scrutiny unreasonableness, substantive legitimate expectations and mistake of fact). Turning from substance to procedure, access to judicial review is more liberal in several respects. Finally, a notable feature of the New Zealand approach across all aspects of administrative law is a marked resistance to rigid doctrinal categories. Reflecting on these differences, the conservative aspects can be seen in the context of the still fairly unqualified adherence to Parliamentary sovereignty, in the absence of a supra-national source of law such as the ECHR or the EU. The other aspects may be seen as reflecting the national identity as a small polity with informal channels of communication, given to pragmatic solutions, and keen to be seen as a good international citizen.

The primary source of law before the Court is the Statute itself and the principal subsidiary instruments, the Elements of Crimes and the Rules of Procedure and Evidence. The Court may also refer to relevant rules of international law, notably those of international humanitarian law and international human rights law. Article 25 of the Statute sets out the various forms of participation in crimes starting with direct perpetration but also including ordering and forms of complicity and attempt. Article 28 defines so-called command or superior responsibility, by which an individual may be held responsible for crimes perpetrated by subordinates. The Court cannot prosecute an individual who was under 18 at the time of the crime. Statutory limitation of crimes within the Court’s jurisdiction is prohibited. There is a presumption that all crimes subject to the Court’s jurisdiction require proof of intent and knowledge. Several defences are codified: diminished mental capacity, voluntary intoxication, self-defence, duress and necessity, mistake of law and mistake of fact and, under limited circumstances, superior orders.

This chapter picks up the historical story in the middle of the twentieth century. Against a background of an enhanced sense of independence and confidence of people and institutions that developed following World War I and World War II, I argue that it was in the middle of the twentieth century, from the 1930s to 1960s, that Australian criminal law came into its own – measured in terms of an orientation around national coordinates, and in the self-confidence of its practitioners and academics. I demonstrate that, with close reference to the decisions of English courts, and commentaries such as that of Glanville Williams – and, increasingly over the period, to US developments like the Model Penal Code – Australian lawyers and commentators came to forge an independent path for the criminal law in the mid-century. Working over and above developments that occurred within state jurisdictions, and across code and common law modes of criminal law, practitioners and scholars were thoroughly engaged in a global debate about the development and improvement of the law of crime, and in a complex and subtle negotiation between what Australia shared with others, and what might be thought mark it out. In the mid-century, it became possible to think about Australian criminal law as such, to conceptualise Australian criminal law as a meaningful idea.