What can a study of social media offer socio-legal studies? Although there are now sophisticated techniques for the analysis of social media, socio-legal studies has yet to draw on them fully. In this paper, we demonstrate how Twitter can produce insights about protest, law and legality. We do so through a case study method, using the so-called bedroom tax. We look at two different ways in which protest against the bedroom tax has been mobilised. The first method involved challenging a policy in the courts using a test case or cases. We discuss the litigation strategies and mess that they created. We counterpose those strategies against those of four prolific ‘tweeps’ who, using a traditional interview method, participated in our study. We argue that, despite the small number of participants, each of these people has in their own way been enormously influential and made things happen. Our position is not an evaluative one – of the different strategies (which, in any event, overlap) – but that legality is mobilised in different ways, different purposes, and our tweeps may well have been, in this case study, rather more successful in their challenges than the lawyers.