How do ICE detention and prosecutorial referrals differ for criminal vs civil cases?
Executive summary
Immigration enforcement is formally a civil administrative system while criminal prosecution is a separate federal process, and that split drives how detention and referrals are handled: ICE uses civil authorities (detainers, removal proceedings, mandatory civil detention for certain criminal categories) but can and does refer criminal conduct to the Department of Justice for prosecution when appropriate (or coordinate with HSI for criminal investigations) [1] [2] [3]. Prosecutorial discretion — exercised across ICE, HSI and ICE attorneys — determines whether a case proceeds as civil removal, is deferred, or is referred for criminal charges, and that discretion shapes who is detained, for how long, and whether a person faces prison time or deportation [4] [5].
1. The legal divide: civil immigration law vs. criminal law
Statutorily, immigration enforcement is a civil framework focused on removal; immigration proceedings are not criminal prosecutions and do not require the same procedural safeguards as criminal cases, which are handled by the DOJ in federal court and can carry prison sentences rather than removal orders [1] [6]. That formal separation means ICE’s core tools—detainers, administrative warrants, and removal proceedings—are designed to achieve deportation, whereas criminal referrals aim at conviction and incarceration and are pursued under separate criminal statutes and evidentiary rules [2] [7].
2. How detention works differently in civil and criminal contexts
ICE holds people under civil statutory authority; for some removable noncitizens (especially those with certain criminal or national-security grounds) detention is mandatory during removal proceedings, while others may be released on bond or alternatives to detention [2]. Local criminal custody interacts awkwardly with civil detention: ICE detainers are administrative requests rather than judicial warrants, and reliance on them has produced litigation and guidance warning that holding someone beyond criminal-release time on a civil detainer can violate constitutional rules and local law [8] [9].
3. Prosecutorial referrals: when ICE triggers criminal action vs civil removal
ICE and its investigative arm HSI can refer cases to the DOJ for criminal prosecution when evidence indicates federal criminal conduct, and those referrals generate criminal charges that are separate from civil removal processes; conversely, many enforcement actions result in administrative removal with no criminal charges, particularly where the focus is unlawful presence or immigration status rather than a separate offense [6] [3]. Guidance and memos (Morton, Doyle, Mayorkas-era directives) clarify which ICE officers and attorneys can exercise prosecutorial discretion to refer, defer, or decline both civil and criminal enforcement, meaning the same agency often decides the appropriate forum [4] [10].
4. Prosecutorial discretion, priorities, and who gets detained
ICE’s use of prosecutorial discretion is explicit: enforcement priorities guide whether someone with a criminal history is prioritized for detention and removal, or instead deferred or released under supervision—policies that aim to concentrate resources on those deemed greatest threats to safety or security [3] [4]. At the same time, advocacy groups and practice advisories document that discretion is applied unevenly and that policies (and unpublished memos) can shift priorities, creating unpredictability for individuals and defense attorneys attempting to negotiate custody redeterminations or ask for deferred action [11] [10].
5. Practical intersections and legal risks at jails and courts
In practice, criminal arrests often trigger immigration consequences: local jails pass fingerprints to ICE, ICE issues detainers, and immigration counsel may seek custody redeterminations or prosecutorial discretion to avoid removal—yet courts have increasingly pushed back on indefinite holds based solely on ICE detainers and flagged Fourth Amendment and due-process concerns [8] [2]. Conversely, criminal convictions can create mandatory civil immigration detention or removability even if no criminal referral occurred, meaning the outcome in one system (conviction) can force action in the other (removal) without a fresh criminal prosecution by the DOJ [2] [3].
6. Competing narratives, agency motives, and limits of reporting
Government documents frame ICE actions as prioritization to protect public safety and system integrity, emphasizing criminal-aliens removal metrics, while immigrant-rights groups and defense attorneys highlight constitutional and humanitarian harms from civil detention and detainer misuse—both perspectives are grounded in agency memos, litigation, and practice advisories that show prosecutorial discretion is powerful but uneven [3] [5] [8]. Reporting and the available sources document processes and policies but do not always reveal case-level decisionmaking or all internal memos; where claims extend beyond those documents this account notes that limitation rather than asserting unverified facts [4] [12].