Reference

Glossary

A working vocabulary for the cases discussed on this site — statutory provisions, leading precedents, and terms of art that recur across the immigration habeas docket.

28 U.S.C. § 2241: The federal habeas corpus statute, descended from the Habeas Corpus Act of 1867. In the immigration context, it is the principal vehicle by which a person in federal custody — including civil immigration detention — may petition a U.S. district court to test the legality of that custody. The statute is silent as to immigration but its reach over executive detention is foundational.
8 U.S.C. § 1225(b): The expedited-removal and arriving-alien detention provision of the INA. Subsection (b)(1) governs expedited removal of those without valid documents; subsection (b)(2)(A) requires detention of "applicants for admission" pending removal proceedings. After 2025, the government has argued — and the Fifth Circuit has agreed in Buenrostro-Mendez v. Bondi (2026) — that this mandatory-detention provision applies to anyone present without admission, even after years of residence.
8 U.S.C. § 1226(a): Discretionary detention authority for noncitizens in removal proceedings, allowing release on bond by an immigration judge. Practically eliminated for "EWI" entrants by the BIA's 2025 precedent decisions and the Trump administration's July 2025 ICE detention directive, except where habeas relief restores it.
8 U.S.C. § 1226(c): Mandatory detention of certain noncitizens with covered criminal convictions, with no statutory bond hearing. Upheld facially in Demore v. Kim (2003) and Jennings v. Rodriguez (2018), it remains subject to as-applied due-process challenges in several circuits when detention becomes unreasonably prolonged.
8 U.S.C. § 1231(a)(6): Post-final-order detention authority. Read by the Supreme Court in Zadvydas v. Davis (2001) to be limited to the period reasonably necessary to effectuate removal — presumptively six months. Beyond that, the petitioner can shift the burden by showing no significant likelihood of removal in the reasonably foreseeable future.
Alien Enemies Act (50 U.S.C. § 21): A 1798 statute permitting the President, in time of declared war or in case of invasion or predatory incursion by a foreign nation or government, to detain or remove citizens of the hostile nation. Invoked four times in U.S. history: the War of 1812, World War I, World War II, and (in March 2025) against Venezuelan nationals alleged to be members of Tren de Aragua.
BIA: The Board of Immigration Appeals, an administrative tribunal within the Executive Office for Immigration Review. Its precedent decisions bind immigration judges nationwide; in 2025, two BIA precedents — Matter of Q. Li and Matter of Yajure Hurtado — reclassified long-resident EWI noncitizens as "applicants for admission" subject to mandatory detention without bond, triggering the modern habeas surge.
CAT (Convention Against Torture): An international treaty implemented in U.S. immigration law via the Foreign Affairs Reform and Restructuring Act of 1998 and 8 C.F.R. §§ 208.16-208.18. CAT bars removal to a country where it is more likely than not the noncitizen would be tortured. Country-specific; does not by itself bar removal to a third country.
CECOT: Centro de Confinamiento del Terrorismo — El Salvador's mega-prison. In March 2025, hundreds of Venezuelan nationals were transferred there from U.S. custody under the Alien Enemies Act and parallel agreements. The conditions of confinement and the U.S. role in directing them have generated extensive litigation, including the "constructive custody" theory advanced by Judge Boasberg.
Constructive custody: The doctrine, advanced by Chief Judge James E. Boasberg in J.G.G. v. Trump (D.D.C. Dec. 2025), that the United States retains a measure of control over noncitizens delivered to a foreign jail at U.S. direction and expense, such that habeas jurisdiction continues despite the petitioners' physical presence abroad.
Demore v. Kim: 538 U.S. 510 (2003). Upheld facial constitutionality of § 1226(c)'s mandatory criminal-alien detention regime. The Court relied on then-current statistics suggesting that such detention typically lasted only a month or so — statistics later acknowledged to have been inaccurate, fueling the modern as-applied challenges.
EAJA: Equal Access to Justice Act, 28 U.S.C. § 2412. Authorizes prevailing parties in certain civil litigation against the United States to recover attorneys' fees and costs. The Tenth Circuit's 2025 decision in Daley v. Choate confirmed EAJA fees are available in § 2241 immigration habeas, joining the Second, Third, and Ninth Circuits and materially expanding the private bar's capacity to bring such petitions.
EWI: "Entered without inspection" — shorthand for noncitizens present in the United States without having been admitted at a port of entry. In 2025, the Trump administration took the position, endorsed by the BIA, that all EWI noncitizens are "applicants for admission" subject to mandatory § 1225(b)(2) detention without bond.
Expedited removal: 8 U.S.C. § 1225(b)(1). A streamlined removal procedure in which an immigration officer, not a judge, orders removal of a noncitizen lacking valid documents. Reviewable only via narrow habeas under § 1252(e). In 2025, expedited removal was extended nationwide to anyone unable to prove two years' continuous presence.
Final order of removal: An administratively final order from an immigration judge or the BIA directing the noncitizen's removal from the United States. Triggers transition from § 1226 to § 1231 detention authority and starts the 30-day clock for petitions for review (PFR) under § 1252.
Habeas (the writ): From the Latin habeas corpus ad subjiciendum: "you should have the body for the purpose of subjecting it." The judicial command directing a custodian to bring a detained person before the court to test the lawfulness of the detention. The Suspension Clause, U.S. Const. art. I, § 9, cl. 2, prohibits suspending the privilege of the writ except in cases of rebellion or invasion.
Jennings v. Rodriguez: 583 U.S. 281 (2018). Held that immigration-detention statutes do not, by their own force, require periodic bond hearings for prolonged detention; remanded the as-applied constitutional claims to the Ninth Circuit. Created the doctrinal opening for the post-2018 prolonged-detention habeas docket.
Johnson v. Guzman Chavez: 594 U.S. 523 (2021). Held that noncitizens with reinstated removal orders pursuing withholding-only relief are detained under § 1231 (not § 1226), and so have no statutory entitlement to a bond hearing. Zadvydas's six-month framework still applies once detention becomes prolonged.
Mathews v. Eldridge: 424 U.S. 319 (1976). The procedural-due-process balancing test applied in many prolonged-detention habeas cases: weigh the private interest, the risk of erroneous deprivation under existing procedures, and the government's interest, including the burden of additional procedures.
Matter of Q. Li: 29 I&N Dec. 66 (BIA 2025). The BIA's May 15, 2025 precedent holding that noncitizens apprehended shortly after entry — even in the interior — are "applicants for admission" subject to mandatory § 235(b) detention and ineligible for § 236(a) bond hearings.
Matter of Yajure Hurtado: 29 I&N Dec. 216 (BIA 2025). Companion BIA precedent (September 2025) holding that immigration judges lack authority to hold bond hearings for noncitizens present without admission. Together with Q. Li, made § 2241 habeas the only practical avenue to a bond hearing for tens of thousands of EWI detainees.
Petition for Review (PFR): The 30-day petition for review of a final removal order filed in the appropriate U.S. court of appeals under 8 U.S.C. § 1252. The exclusive vehicle for challenging an administratively final removal order; not a substitute for habeas review of detention legality.
Reinstatement of removal: 8 U.S.C. § 1231(a)(5). Allows DHS to reinstate a prior removal order against a noncitizen who reentered after removal, without a fresh hearing. Reinstated removal orders place the noncitizen in § 1231 detention and limit available relief to withholding and CAT.
Suspension Clause: U.S. Const. art. I, § 9, cl. 2: "The Privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it." Establishes a constitutional floor on habeas review even against statutory restrictions.
Tren de Aragua (TdA): A Venezuelan transnational criminal organization. Designated a Foreign Terrorist Organization in February 2025 and identified by the March 2025 presidential proclamation invoking the Alien Enemies Act as a "foreign nation or government" conducting an "invasion or predatory incursion" of the United States — characterizations that have been rejected by virtually every federal court to consider them on the merits.
Withholding of removal: 8 U.S.C. § 1231(b)(3). A statutory bar to removal of a noncitizen to a country where life or freedom would be threatened on a protected ground. Country-specific; does not preclude removal to a third country in which no such threat exists.
Zadvydas v. Davis: 533 U.S. 678 (2001). The foundational post-removal detention case. Read § 1231(a)(6) to authorize detention only as long as reasonably necessary to effectuate removal; established the six-month presumptively reasonable period and the burden-shifting framework that drives most modern post-removal habeas litigation.
Zipper clause: 8 U.S.C. § 1252(b)(9), which channels "all questions of law and fact... arising from any action taken or proceeding brought to remove an alien" into the petition-for-review process. Increasingly invoked by the government to defeat habeas jurisdiction over First Amendment retaliation and other detention challenges, as in the Third Circuit's January 2026 ruling in Khalil v. Joyce.