When people call out for justice to be done in response to an horrific crime, or when they lament the absence of justice for those who are impoverished in a wealthy world, or when there are outcries against the unjust treatment of one category of people compared with another, each is referring to different ideas of justice. The meaning of ‘justice’ has been the subject of philosophical debate for millennia and, within such analyses, ‘criminal justice’ is sometimes scarcely mentioned while for others it is deeply entwined. With its connection to ideas of virtue and moral ethics, there is a marked contrast between the ways in which the word ‘justice’ has traditionally been used, and the ways in which government, politics and the media now use the expression ‘criminal justice’. More recently, the expression is mostly used to refer to the process that leads from the investigation of an alleged offence to the conviction and sentence of an offender, and so to the point at which the sentence has finally been served; or it may be used descriptively for the structures, services or legislation that are involved in that process. ‘Justice’ is then seen as the outcome of a trial, where the test of whether ‘justice has been done’ is likely to be whether the verdict and sentence satisfy the victim or public opinion, or whether they will be effective in protecting the public.

The purpose of this chapter is to provide a context and a framework of principles for the discussion of more specific issues that follow in later chapters. It considers, first, different theoretical positions on the meaning and importance of justice, the rule of law, and what are sometimes called ‘procedural justice’ and ‘equality before the law’ and their connections with ideas of fairness and legitimacy. These ideas have important practical applications: they are about what gives the law, the criminal justice process and the criminal justice services their authority, why people comply with them, and how that authority can be sustained and protected.