Administrative decision makers may be given a discretionary power under a statute or required to perform a duty. Of these two, the law relating to the exercise of a discretionary power has been the greater subject of substantial jurisprudence and academic commentary. The central debate in this context is the extent to which administrative law should constrain the exercise of discretion – that is, how to achieve a balance between ensuring that decision makers consider the merits of individual cases, whilst also recognising the bureaucratic imperatives of consistency and efficiency. In this respect, this topic presents a challenge for administrative law which must (to some extent at least) reflect the political reality of administrative decision-making, whilst also ensuring that decisions are made lawfully.

The common thread in the jurisprudence in this area is that a decision maker granted power by Parliament under a statute must be the person to make the decision. Thus he or she cannot fetter that discretion, improperly delegate to another or, if a duty is applicable, fail to perform that duty. Before discussing the grounds for judicial review which arise in this respect, it is necessary to discuss the meaning of the term ‘discretion’ in administrative law and to set the grounds in their political context.

The meaning of discretion

The term ‘discretion’ indicates the existence of a level of choice in making a decision and is usually expressed by use of the word ‘may’ in a statutory provision.