In this paper we consider some of the ethical challenges inherent in the regulation of discretionary police power. Discretion is central to police policy and practice, but it also provides a level of freedom that opens up the space for injustice and inequity, and this is seen most vividly in recent debates about unfairness and racial profiling in the distribution and experience of police stops in the US and UK. How to regulate discretionary power is a challenging question, and this is especially so in the context of practices like stop-and-search/stop-and-frisk. The ability to stop people in the street and question them is central to policing as it is understood in many liberal democracies, but under conditions of unfairness and questionable efficacy – when the application of this particular police power appears unethical as well as ineffective – one can reasonably ask whether the power should be dropped or curtailed, and if curtailed, how this would work in practice