This study examines the development of police stop and search in Scotland from the post-war period onwards. The aim is to explain the remarkable scale of stop and search, the attendant lack of political or academic engagement prior to the formation of the single service in in April 2013, and to draw out the implications, both for policing and the public. The thesis takes a top-down perspective which seeks to explain the policing direction in terms of elite outlooks and decision-making over time. It is argued that search rates in contemporary Scotland can be explained in terms of an incremental shift in the way that the tactic has been conceptualized by political and policing elites. Specifically, it is argued that the post-war construct of stop and search as a reactive mechanism premised on investigation, detection and the disruption of crime, has been displaced by a proactive model, premised on intensive, risk-based stop and search activity. It is argued that this shift has partly attenuated the link between stop searches and suspicious behaviour by introducing non-detection as a measure of successful deterrence, alongside the traditional aim of detection. In short, it is argued that stop and search has been remodelled as a tactic that can be legitimated irrespective of the outcome. The thesis will show how this shift has progressively weighted the balance between crime control and individual freedom in favour of the state, and weakened the rights of the individual, with minimal regard for procedural protection and human rights. The thesis employs a wide range of data sources and methodologies to investigate the core argument, which is developed from three interrelated positions. First, taking a historical perspective, the thesis examines elite sensibilities and decision-making in relation to stop and search from the early 1950s, through to the early 2000s. Next, the thesis adopts an empirical position to investigate the use of stop and search between 2005 and 2010, and shows how search activity on the street reflected dominant outlooks higher up the ranks. Finally, the thesis adopts a normative perspective in order to assess the ethical implications of stop and search practice in Scotland, and to develop a series of informed recommendations for policy and practice.