This chapter explains that the General Law on Disappearances in Mexico is a legal change achieved by a broad mobilisation of families of victims of disappearance in a challenging context of persistent violence in the country. The Law helps to improve the relevant standards related to searching for disappeared persons, guaranteeing the rights of the victims’ families, furthering the investigation of forced disappearance caused by the government and/or individuals, as well as creating the institutional structures focused on the search for persons. Despite this, the law’s innovative advances coexist alongside previous institutional mechanisms that perpetuate practices contrary to the rights of victims and their families, which risk neutralising the Law. Accordingly, the chapter focuses on the promotion of legal mobilisation strategies in countries, such as Mexico, which accept normative and institutional changes without worrying about their enforcement, since, in practice, new provisions clash with previously created structures that have similar legal authority but greater decision-making power, and are, thus, better able to exercise that authority.