Abstract This article offers an approach to the relationship between international law (IL) and Latin American social movements (LASM). In the first place, it reminds the two-way interplay of LASM with some international institutions and rules. It then moves to discuss certain LASM experiences with IL ranging from questioning it and using it from an alternative perspective, to deliberately reformulate its terms and seek better ways to use it in daily struggles. It highlights LASM practices regarding institutional arenas and, more importantly, extra-institutional mobilization. Thus, this contribution attempts to show the richness, creative, and pressing value of LASM uses of IL, beyond any pretension of purism or correctness. At the bottom of this chapter is a challenge to the assimilations and institutional registry of social movements as subaltern users of IL, which fits the lack of genuine popular influence in global decision making.