At the U.S.–Mexico border, migrants have faced cruel treatment in the form of policies aimed at deterrence, as well as facilities lacking the capacity to treat migrants with dignity if they are apprehended by the Department of Homeland Security. In this paper, I use moral responsibility and atrocity crime frameworks to interrogate the responsibility of the individuals and collectives that are either bystanders to, or directly responsible for, the conditions of these migrants. In constructing frameworks for accountability, I argue that we must acknowledge the wrongdoing of past collectives, individuals, and bystanders in order to ensure a sharp change in future policies, and that moral responsibility allows us to do so more effectively.