This chapter will analyse the array of mechanisms that have been developed to control the way in which police discretion is exercised and to enhance the accountability of police officers for operational decisions. Some issues related to this topic in connection with chief officers (in particular relating to the formulation of police priorities which raises the issue of operational accountability) have been covered in earlier chapters in this work and thus the main thrust of the chapter will be concerned with issues affecting the discretion of junior officers by examining the mechanisms that hold him or her accountable for the decisions they take when performing their duties. The chapter will chart the development of formalized police complaints machinery that addresses issues such as abuse of power and consider the adequacy of the arrangements that have been constructed which now entail the role performed by the Independent Office of Police Complaints (IOPC). It will further evaluate issues related to the conduct of officers ‘on the streets’. These include issues such as disproportionality in the use of stop and search procedures. Contemporary developments such as those arising from the introduction of the National Decision Model (in particular the Police Code of Ethics that sits at the heart of this model of police decision-making) and the introduction of body-worn video cameras by police officers will also be evaluated in this chapter as methods used to scrutinize and place limits upon the unbridled use of discretion by individual officers.