Laws restricting collaboration between local police and federal immigration agencies (also known as “sanctuary city” policies) reemerged after 9/11, concurrent with the federal restructuring of immigration enforcement. Across the U.S., local communities pushed back against the post-9/11 rhetoric of immigrant threat and criminality, as well as the federal government’s hawkish immigrant detention and deportation programs. Cities, counties, and even states formally rejected federal initiatives seeking to use local police as key players in immigration enforcement. These jurisdictions resisted the notion that the indefinite detention of unauthorized immigrants was an appropriate response to the threat of terrorism, international drug trafficking, and gang violence. Nevertheless, contemporary scholarship frames the Homeland Security movement as an overwhelming cultural and political force requiring deference to the federal government’s conception and pursuit of “security.” The sanctuary movement calls for a reconsideration of this now well-accepted American narrative. How did sanctuary jurisdictions overcome the American carceral impulse that many scholars have described as hegemonic in the late 20th and early 21st centuries? More broadly, why do narratives of social threat take root in within certain social contexts and not others? And what might this tell us about the phenomenal growth in American criminal administration and imprisonment in the latter half of the 20th century? The project is built around the Weberian concept of legitimacy, and attempts to shed light on the relationship between conceptions of social threat and the extension of police administration.