Do sanctuary cities report undocumented felons?
Executive summary
Sanctuary policies are not a uniform legal shield that prevents local authorities from arresting, reporting, or enabling the deportation of undocumented people accused of felonies; rather, most sanctuary jurisdictions limit certain types of cooperation with federal immigration enforcement—especially honoring ICE detainer requests or automatic information-sharing—while continuing to enforce state and local criminal laws and to process arrestees in ways that can lead to federal immigration checks [1] [2] [3].
1. What “reporting” means in practice: fingerprints, booking data, and detainer requests
When local police arrest someone in the United States they typically take fingerprints and submit booking information to the FBI, which can be queried by ICE, so an arrest for a felony still creates a pathway for federal immigration authorities to identify and pursue an undocumented arrestee even in a sanctuary jurisdiction [4]; sanctuary rules most commonly govern whether local agencies will detain someone longer on an ICE detainer or proactively share non-routine immigration information, not whether they will document or arrest felons under state law [5] [1].
2. Sanctuary policies vary — there is no single national rule
“Sanctuary” covers a spectrum: some places adopt narrow rules refusing to honor civil ICE detainers except for serious violent felonies, others limit almost all information‑sharing, and some localities add employee non-cooperation clauses or ban notifying federal agents about immigration status; because policies differ widely, whether a specific undocumented felon will be handed to ICE depends on local ordinance, exceptions in the policy, and the charging facts [5] [6] [3].
3. Evidence on outcomes: deportations of violent offenders and crime rates
Multiple peer‑reviewed studies and major research syntheses find that sanctuary policies did not measurably reduce deportations of people with violent convictions, nor did they increase local crime rates; for example, a PNAS analysis combining ICE deportation and FBI crime data found no evidence that sanctuary policies prevented deportations of people with violent convictions and detected no increase in crime in jurisdictions that adopted such policies [4]; other academic work likewise shows little or no adverse public‑safety effect and notes potential benefits in encouraging crime reporting by immigrant victims and witnesses [7] [8] [9].
4. Critics and politics: claims that sanctuaries “shield criminals”
Political critics and some federal actors frame sanctuary rules as obstructing enforcement and protecting criminal aliens, asserting that some jurisdictions “forbid” sharing information or turning over criminals to ICE; congressional Republicans and White House statements have used such language to press for withholding federal funds and stricter penalties, and hearings have amplified anecdotes of recalcitrant local cooperation [10] [11]. That narrative conflicts with legal and empirical findings showing sanctuary policies typically do not eliminate the mechanisms by which ICE identifies arrestees [1] [2].
5. Practical reality and limits of the evidence
The practical effect is mixed and case‑specific: many sanctuary cities still arrest and book undocumented felons and their data flow to federal databases; some jurisdictions will comply with ICE if the person is wanted for a serious violent felony or after judicial process, while others refuse most detainers—local discretion, state laws, and court rulings matter [5] [6]. Reporting limitations in available sources mean a universal, across‑the‑board yes/no answer cannot be stated for every city or county: the weight of legal analysis and empirical studies, however, indicates sanctuary policies typically do not prevent the detection or deportation of undocumented individuals who commit serious crimes [1] [4].