In the context of the war on drugs, undocumented international migration in Mexico is facing a serious human rights crisis. Each year, hundreds of thousands of migrants, above all from Central America, cross Mexico to reach the United States. Through their journey they risk extortion, kidnap, ill treatment, torture, forced disappearance, forced labour, sexual abuses, and death. Ironically, in the last few years, migrants’ rights has become a profession for many people. Never before have there been so many rights-based organisations and human rights practitioners in Mexico working in the promotion and defence of migrants’ rights. This article is a sociologically driven analysis that seeks to critically examine the role of human rights organisations and practitioners working in the field of transmigrants’ rights in Mexico. The article analyses how human rights practitioners and rights-based organisations talk about the suffering and violence routinely experienced by transmigrants in Mexico; and identifies the most visible implications of that discourse. It argues that legalism over-dominates practitioners’ work and agendas: practitioners address the problem of undocumented migration through a narrow legalistic lens that ignores or fails to challenge the wider political and social conditions that make the abuses possible in the first place.