Over the past two decades, the US government has expanded immigration detention to unprecedented levels. This essay explores the social and doctrinal origins of the immigration detention boom and provides a critique of the legal doctrines that continue to insulate immigration detention from the legal scrutiny generally applied to comparable deprivations of liberty in the context of criminal punishment. The article also evaluates recent immigration detention reform efforts and their limitations, assessing the potential impact of current immigration reform proposals on immigration detention. Notwithstanding the apparent trend in favor of immigration reform, viable reform proposals continue to assume the need for punitive detention for migrants as part of a criminalized immigration enforcement model. In this context, truly comprehensive reform of immigration detention practices in the United States remains a distant goal.