Administrative justice is traditionally considered as the main alternative to the criminal justice system when a certain illegality is decriminalized or not enforced by criminal justice institutions (e.g. the regulation of elite deviance, urban disorder, mental health, etc.). This doctoral thesis studies how the conflicts related to immigration are being managed in the largest administrative tribunal in Canada: the Immigration and Refugee Board (IRB). It asks how exactly does immigration justice, and administrative law more broadly, constitute an alternative to criminal justice in terms of social reaction, and what kinds of challenges does this alternative present for the study of social control. This research takes a qualitative approach based on documentary analysis and long-term ethnographic fieldwork conducted at the IRB between 2007 and 2009. It uses its own theoretical framework building on post-structural perspectives, including Bourdieu’s constructivist structuralism, governmentality and nodal governance studies, left realism and political economy of punishment. In the empirical part of the thesis, I present some of the characteristics of the legal translation of conflicts in immigration law, including the forms and logics of punishment involved and how immigration law is practiced at the tribunal. I argue that administrative adjudication and punishment differ substantially from criminal law regimes and I question the idea of criminalization (of immigration) as a category capable of nuancing the complexity of administrative forms of social reaction. Instead, I suggest that we should take these forms of punitive social reaction as they are, and study how they operate along, beyond and in addition to criminal law. I propose an integrated conception of the penal complex which works as a mobile (kinetic sculpture) and includes the criminal law realm, but also other normative systems that configure ‘less’ prominent locations of punishment playing an increasing role in social reaction. I conclude by proposing a new reading of selectivity of justice and penal policies, and consequently, a new agenda for criminology and criminologists. In this new agenda, the penal complex should be taken as a totality in order to promote broader and combined propositions for law reform and resistance to punitiveness.