1. Introduction

This book focuses on substantive criminal law, that is, how offences such as theft and murder are defined. This introductory chapter sets in context criminal offences and defences, first by considering the basis upon which certain conduct is criminalised and other conduct is not. It then outlines the reasons why people commit crimes, which types of people commit them, and whether certain groups are over-represented in criminal statistics. It also discusses the role of evidence in assessing how well criminal offences can be proved in practice; the punishments for committing crimes; the difference between criminal and civil law; the process and procedure to obtain a criminal conviction; sources of the substantive criminal law; the internal structure of offences and defences; principles of the substantive criminal law and the subjects to which it applies; legal reform; and the application of the current law.