Law-based, civic-led advocacy has long been an important means for addressing rule of law deficits and problems of development and governance more generally. Authoritarian regimes, official and/or corporate foreign-based corruption and the structural limitations of formal rule of law mechanisms to deliver impartial justice have forced legal advocates to think creatively. This has resulted in some interesting examples of civic-led, law-based advocacy through both informal and formal structures, aimed at pursuing social justice. However, it is important to clearly distinguish legal mobilisation from illegitimate forms of legal instrumentalism, such as lawfare. In this Working Paper, I set out some of my current research ideas in this area and in particular explain my approach to researching legal mobilisation, which I regard as a practice as well as a socio-legal concept and approach, with a particular emphasis on the use of law as a form of political legitimacy.