In recent years, there has been an increased focus on the use of the precautionary principle within counter-terrorism. To date much of the literature has focused on ‘high’ level executive measures. This article examines the use of the precautionary measures within counter-terrorism street policing, taking suspicionless counter-terrorism stop and search as an exemplar. The analysis highlights how the logic of precaution necessitates vague statutory drafting and extensive police discretion and how these factors detrimentally impact upon police legitimacy and compliance to human rights law. It also considers how such measures fit within the current literature on pre-crime.