14. General defences

This chapter deals with general complete defences that the accused can use to avoid liability. The focus is on defences that can apply (with one exception) to offences throughout the criminal law and will result in the accused’s acquittal. Five kinds of general complete defences are examined: insanity (as a defence), duress by threats, duress by circumstances, the public and private defence (also known as self-defence), and necessity. The chapter first considers the categorical division between excuses and justifications, before explaining the elements of each of the defences in turn. It then outlines potential options for legal reform concerning individual defences and concludes by discussing the application of the general defences to problem facts. Relevant cases are highlighted throughout the chapter, with brief summaries of the main facts and judgments.