Within the criminal justice system, the presence or absence of discretion is one of the most important determinants of whether or not the system secures justice for all parties and participants. The question is where justice lies on the spectrum running between criminal law by rules and criminal law by decision. Prosecutors in German and Anglo-American criminal law occupy distinctive roles, as decision-makers, due to both the institutional and normative framework, and the presence of both role duality and role ambiguity. Since prosecutorial discretion in the context of an investigation cannot be separated from police discretion, this chapter covers all discretionary decisions during the proceedings by prosecutors and the police. The chapter thus only deals with discretionary decisions of other agents (such as judicial discretion) from a conceptual perspective since the particular, constitutionally protected position of judges affects their discretion considerably. In the words of the German Constitutional Court: ‘Police forces and public prosecutors do not enjoy independence and cannot be expected – with regard to their investigatory powers and duties – to show the same strict neutrality as judges do.’

Criminal law and criminal justice are becoming increasingly globalised. In open societies, the era in which individual jurisdictions developed their own codes, statutes and systems of justice with no regard to other systems and countries is long over. There is a growing desire to develop common approaches to common problems and to learn from the diversity of current practice in different countries. This development has been reinforced by the internationalisation of criminal justice in international and mixed criminal tribunals. However, attempts at trans-jurisdictional discourse are often hampered by mutual misunderstandings. Some problems are linguistic: although English is the new lingua franca of international and comparative criminal law, not all foundational concepts of criminal law and justice originate in the English-speaking world; some of them are rooted in civil law jurisdictions, such as France, Germany and Italy. The translation of these concepts into English is subject to ambiguity and potential error: the same term may assume different meanings in different legal contexts.

The prosecutor’s position within the criminal justice system cannot be overstated. Robert Jackson, former United States Attorney General, who gained worldwide reputation through his role as Chief United States Prosecutor at the International Military Tribunal in Nuremberg, remarked fully seventy-five years ago that: ‘The prosecutor has more control over life, liberty, and reputation than any other person in America.’ Prosecutors are ‘the criminal justice system’s real lawmakers’ and ‘the gatekeepers to the justice system’ system’, insofar as they make the crucial decisions about which individuals enter the criminal justice system and under what conditions they move through it.