The federal government has increasingly advanced an expansive theory of immigration detention: that once Congress designates a noncitizen as “inadmissible” and subjects that person to mandatory detention, the constitutional inquiry all but disappears.
Yesterday, the Ninth Circuit rejected that proposition in emphatic terms.
In Padilla v. U.S. Immigration and Customs Enforcement, No. 24-2801 (9th Cir. Sept. 21, 2026), a published decision, the Court of Appeals held that Department of Homeland Security v. Thuraissigiam does not extinguish the Fifth Amendment rights of immigrants who are physically present within the United States merely because they entered without inspection.
The holding is important not because it announces some novel constitutional innovation, but because it restores a principle that should never have been controversial: the Fifth Amendment protects persons, and immigration status does not place a human being beyond the Constitution’s protection against arbitrary governmental confinement.
As the Ninth Circuit reiterated:
“The Due Process Clause applies to all ‘persons’ within the United States, including aliens.”
That rule rests on more than a century of Supreme Court precedent. Yet its reaffirmation carries particular force at a moment when the government has sought to enlarge mandatory detention far beyond the geographic and doctrinal confines of the border itself.
The Question in Padilla Was Not Whether Congress May Regulate Admission. It Was Whether the Government May Imprison Without Meaningful Constitutional Constraint.
The plaintiffs in Padilla are asylum seekers who entered the United States without inspection, were placed into expedited-removal screening, established a credible fear of persecution or torture, and were thereafter transferred into regular removal proceedings.
They remained detained pursuant to 8 U.S.C. § 1225(b)(1)(B)(ii). That statutory posture matters. In Jennings v. Rodriguez, the Supreme Court held that § 1225(b) does not itself provide the periodic bond hearings that the plaintiffs sought. But Jennings answered a question of statutory interpretation. It did not resolve the distinct constitutional question presented when detention becomes prolonged and the government refuses to provide any individualized mechanism for testing whether continued incarceration remains justified.
That is the question Padilla places squarely before the courts:
What process does the Constitution require when the government continues to deprive a person of physical liberty?
The government urged dismissal, relying heavily on Thuraissigiam and arguing, in substance, that people who entered unlawfully lacked procedural due-process protections beyond those Congress had chosen to afford them. The Ninth Circuit rejected that reading.
A Legal Fiction Concerning Entry Cannot Become a License for Constitutional Erasure
Thuraissigiam involved a man apprehended almost immediately after crossing the border, approximately 25 yards inside the United States.
The Supreme Court treated him, for purposes of admission, as functionally standing at the threshold of entry.
The government in Padilla, however, sought to transform that limited doctrine into something far more sweeping.
Under the government’s theory, the so-called “entry fiction” could continue to govern individuals apprehended deep within the territorial United States, including people who had been physically present for substantial periods of time. The legal consequence would be extraordinary: a doctrine historically tied to admission at the border would become a mechanism for narrowing constitutional protection against detention throughout the interior of the country.
The Ninth Circuit declined to permit that doctrinal expansion.
The entry fiction, the Court recognized, is precisely that: a legal fiction deployed for a defined purpose. It does not render the Constitution geographically or temporally irrelevant once a person has entered the country and is physically present within it. Nor does unlawful entry eliminate the constitutional status of the person who entered.
That distinction is foundational. Immigration law may classify a person as inadmissible. It may authorize removal. It may impose statutory detention. But none of those legal classifications alters the constitutional proposition that a human being physically present within the United States remains a “person” for purposes of the Fifth Amendment.
The Power to Exclude Is Not Synonymous With the Power to Imprison
The most consequential feature of Judge Marsha Berzon’s opinion is its insistence on separating two governmental powers that are too often collapsed into one another: the sovereign power to regulate admission and removal, and the coercive power to deprive a person of physical liberty.
Those powers are related, but they are not constitutionally identical.
Thuraissigiam concerned admission. The plaintiff there sought additional judicial review of an adverse credible-fear determination bearing on whether he could remain in the United States.
Padilla concerns incarceration.
That difference is not semantic. It goes to the core of the Anglo-American constitutional tradition.
The opinion situates the prohibition on arbitrary imprisonment within a lineage extending from Magna Carta, through the development of habeas corpus and due process in English law, to the constitutional architecture of the United States. The judiciary’s historic role in scrutinizing executive detention did not arise accidentally. It arose because unchecked physical confinement has long been understood as among the most dangerous exercises of state power.
The Court invoked Blackstone’s warning against imprisonment as a:
“dangerous engine of arbitrary government.”
That phrase resonates precisely because immigration detention is civil detention. It is not a criminal sentence. It is not punishment imposed after conviction. And the government’s authority to regulate migration does not itself answer the separate constitutional question of when continued imprisonment is justified, by what evidentiary showing, and subject to what procedural safeguards.
“Mandatory Detention” Is a Statutory Description, Not a Constitutional Conclusion
This distinction is indispensable.
When Congress provides for detention under § 1225(b), that answers a statutory question: what authority has Congress conferred upon the Executive?
It does not necessarily answer the constitutional question: what limitations does the Fifth Amendment impose upon the exercise of that authority?
Those are different inquiries.
Jennings held that § 1225(b) cannot be rewritten to contain bond-hearing requirements Congress did not place there. But the absence of a statutory hearing procedure does not transform detention into a constitution-free zone. If anything, the absence of statutory safeguards makes the constitutional inquiry more, not less, significant.
The government’s position in Padilla would have collapsed those two questions into one. If the statute authorized detention, and if Congress had not provided a hearing, then the analysis would effectively end.
The Ninth Circuit refused that shortcut.
A statute may authorize detention. It does not thereby immunize the detention from constitutional scrutiny.
That principle is especially consequential as immigration enforcement moves increasingly into the interior, ensnaring people with homes, families, employment, community ties, and substantial periods of physical presence in the United States.
The government sought to transform a doctrine concerning the threshold of admission into a broader theory that would determine whether people already present within the country may invoke constitutional protection against arbitrary incarceration.
The Ninth Circuit declined to endorse that theory.
What the Ninth Circuit Decided, and What Remains Unresolved
The significance of Padilla should not be overstated. The Ninth Circuit did not hold that every member of the plaintiff class is automatically entitled to a bond hearing. Nor did it determine the precise procedural framework the Fifth Amendment ultimately requires.
The appeal arose at an interlocutory stage, following the district court’s refusal to dismiss the constitutional challenge. The Ninth Circuit resolved two antecedent questions: first, that the federal courts possess jurisdiction to adjudicate the constitutional claim; and second, that Thuraissigiam does not foreclose that claim merely because the plaintiffs entered the United States without inspection.
The litigation will continue. But that procedural posture does not diminish the importance of the principle the Court preserved. The government may not dispose of a constitutional challenge to prolonged civil detention simply by invoking unlawful entry and asserting that due process therefore has nothing further to say.
For immigrants physically present within the United States, Padilla rejects that proposition.
Due Process Is Not an Immigration Benefit
At LaL Legal, we litigate immigration detention cases in federal court because immigration authority and detention authority cannot be treated as interchangeable concepts.
A bond hearing does not confer lawful status. A writ of habeas corpus does not grant a green card. A constitutional challenge to detention does not resolve whether a person ultimately has a legal right to remain in the United States.
Those are different questions. Due process asks something more fundamental: when the government restrains a person’s physical liberty, what must it prove, and what procedures must it provide, to justify continuing that restraint?
That inquiry is not collateral to constitutional liberty. It is one of its oldest and most essential forms. The central lesson of Padilla is therefore both modest and profound. Immigration law operates within the Constitution, not beyond it. The government may regulate admission. It may pursue removal. It may exercise powers Congress has lawfully conferred.
But when it imprisons a human being, the Constitution remains present.
And the judiciary remains obligated to ask whether that imprisonment is lawful.