I. Introduction 

U.S Immigration Detention undermines international human rights law when it restricts liberty without adequate justification or exposes individuals to harmful conditions. The United States is a party to the International Covenant on Civil and Political Rights, which prohibits arbitrary detention and mandates that people deprived of liberty be treated with humanity and dignity. Europe, like the United States, is a primary destination for migrants and relies heavily on administrative detention to manage large migrant populations (Heartland Alliance’s National Immigrant Justice Center (NIJC) and Physicians for Human Rights (PHR), 2012). Given that European states have faced similar migration pressures, their legal systems provide guidance on how international human rights standards apply to immigration detention.

Under those standards, the routine and prolonged use of solitary confinement in U.S. Civil Immigration Detention constitutes arbitrary detention under international human rights law. Although immigration detention is authorized under domestic law, the use of isolation without individualized necessity determinations, meaningful review, or enforceable safeguards violates the requirements of proportionality and humane treatment under Articles 9 and 10 of the International Covenant on Civil and Political Rights. European case law conveys how these international standards operate in comparable detention systems and ascertains whether current U.S. practices comply with those obligations.

II. U.S. Civil Immigration Detention and the Use of Solitary Confinement

Immigration detention in the United States is classified as a civil, administrative system rather than a criminal one. Immigration authorities detain individuals during pending removal proceedings, often under discretionary authority. (Immigration Detention: A Legal Overview, 2025). Within this civil detention system, however, the United States routinely uses solitary confinement, referred to administratively as “segregation” or “restrictive housing” across immigration detention facilities (Physicians for Human Rights, 2025; Cuffari, 2021). According to Physicians for Human Rights, U.S. Immigration and Customs Enforcement (ICE) places thousands of individuals in solitary confinement each year. Individuals in solitary confinement are typically sequestered in their cells for 23 to 24 hours per day, with extremely limited human interaction. Many remain in solitary confinement for weeks or months, and in some documented cases, for even periods as long as 567,652 and 759 days. (Physicians for Human Rights, 2025). ICE uses solitary confinement for a wide range of reasons, among them disciplinary measures, so-called “protective custody,” medical or mental health concerns, and operational issues such as staffing shortages or lack of space within facilities (Physicians for Human Rights, 2025; Cuffari, 2021).

Oversight reports have documented significant harm associated with the use of solitary confinement in immigration detention. Physicians for Human Rights a U.S.-based non profit, NGO found high rates of mental health deterioration among individuals placed in isolation, including increased anxiety, depression, hallucinations, self-harm, and suicide attempts (Physicians for Human Rights, 2025). The Department of Homeland Security’s Office of Inspector General similarly reported that solitary practices worsen existing mental health illnesses and are sometimes implemented in circumstances where less harmful alternatives are available (Cuffari, 2021).

The use of solitary confinement has also been documented in facilities with records of oversight failures. For example, Eloy Detention Center, a private facility in Arizona operated by CorecIvic has been described by advocates as one of the deadliest immigration detention centers in the U.S. A 2024 report documented at least 16 reported deaths in the facilty’s history, including 5 suicides alonge with systemic failsures such as medical neglect, delayed tretament, ad the excessive use of of isolation in environments that already have severe health and safety issues (Immigrant Accountability Project, 2024). Despite these findings and a 2020 congressional investigation that revealed falsified logs to cover up lack of monitoring for a man in isolation who died of a heart attack, the facility has continued to receive contract extensions (Detention Watch Network, 2025). 

Judicial records further confirm that solitary confinement functions as a disciplinary tool within civil immigration detention. In Menocal v. GEO Group, detainees at the Aurora ICE Processing Center alleged that individuals were threatened with or placed in solitary confinement for refusing to perform cleaning work (22-1409 - Menocal, et Al. V. GEO Group [11130504] | Tenth Circuit | the United States Court of Appeals, 2024). These various situations have repeatedly demonstrated that Solitary confinement is not the last measure within U.S. immigration detention. Rather, it is a routine practice used for a variety of administrative and disciplinary purposes, often for prolonged periods of time. 

III. International Legal Standards Governing Arbitrary Detention

A. The ICCPR: Articles 9 and 10

International law sets legal standards governing the deprivation of liberty in the immigration detention context. For instance, ICCPR, Article 9 protects the liberty and security of a person and regulates the withholding of liberty. This statue requires that no one be subject to ‘arbitrary’ arrest or detention, and that any deprivation of liberty follows the procedures established by law. Specifically, that a detained individual be informed of the reasons for their arrest and any charges, that they be brought before a judicial authority, and that they have the right to challenge the lawfulness of detention (ICCPR art. 9 (1)-(4)). Article 9 also mandates remedies for unlawful detention (ICCPR art. 9 (5); Council of Europe, 1950). These protections apply regardless of the classification of the detention, whether that be criminal, administrative, or immigration-related. In addition, ICCPR’s Article 10 requires that all individuals deprived of their liberty be treated with humanity and with respect for their inherent dignity. 

B. The European Convention on Human Rights

Moreover, the European Convention of Human Rights (ECHR) also has measures relevant to immigration detention. Article 5 enumerates when the deprivation of liberty is permissible under the European Convention. Paragraph (f) of this article allows lawful arrest or detention “of a person against whom action is being taken with a view to deportation or extradition" (ECHR Art. 5(1)(f)). Article 5 recognizes that detention may be used in matters of immigration but also has convention procedural safeguards, including the requirement that detention not be arbitrary and that individuals have access to review of the lawfulness of their detention (ECHR art. 5(1), 5(4); Council of Europe, 1950). 

ECHR Article 3 moreover prohibits torture, inhumane or degrading treatment in any circumstance (ECHR art. 3). Article 46 states that parties must abide by final judgments of the European Court of Human Rights in any case to which they are parties (ECHR art. 46). Therefore, ECHR case law interpreting Articles 3 and 5 has binding force on states within the convention system and has authoritative interpretative power for the meaning of those rights (ECHR arts. 3, 5, 46; Council of Europe, 1950). 

Moreover, the Human Rights Committee, General Comment No.35, has an authoritative treaty body interpretation of ICCPR Article 9. General Comment No.35 clarifies key points in the International Law assessment of immigration detention. For instance, the Committee explains that any deprivation of liberty must be authorized by law and carried out in accordance with law (Human Rights Committee, General Comment No. 35, para. 11). The committee also emphasizes that legality requires domestic rules to be accessible, sufficiently precise, and foreseeable when they apply the law (Human Rights Committee, General Comment No. 35, paras. 11-12). The committee states that national law is ‘not always the decisive element’ in assessing whether detention is justified (Human Rights Committee, General Comment No. 35, paras. 15-16).

Additionally, the committee interprets ‘arbitrariness’ to show not only the lack of legal basis but also elements of injustice, lack of predictability, and the failure to respect necessity and proportionality (Human Rights Committee, General Comment No. 35, paras. 7-8, 12). Detention is arbitrary if it is not necessary in the circumstances of the individual case, like if there were less intrusive means that were available and not considered (Human Rights Committee, General Comment No. 35, paras. 12 & 38).

The committee also requires an individualized assessment before detention is ordered and a reassessment while detention persists. Detention must also pursue a legitimate objective and be strictly necessary and proportionate to that objective in the individual's case (Human Rights Committee, General Comment No. 35, paras. 12 & 18). For example, mandatory or automatic detention rules that remove assessment are incompatible with Article 9 (Human Rights Committee, General Comment No. 35, para. 39). 

The committee also emphasizes that there must be prompt access to judicial review and effective remedies under Article 9 (4)-(5). Judicial review must be ‘without delay,’ allowing access to counsel and relevant information. This requirement allows the individual detained to contest the lawfulness of detention and to have the authority to order release when detention is not justified (GC No. 35, paras. 39 & 46). Additionally, the committee emphasizes that lawfulness encompasses the conditions and treatment of people detained. States must give special regard to vulnerable individuals and ensure that detention does not expose them to unacceptable risks (GC. No.35, para. 9 &18)

IV. European Case Law on Solitary Confinement and Immigration Detention

The European Court of Human Rights has had cases to offer interpretative guidance of Article 3 and Article 5 of the Convention. Their purpose is essentially doctrinal, to clarify when detention conditions cross the threshold of inhumane or degrading treatment and when detention becomes arbitrary or unlawful. 

A. A.B. v. Russia: Prolonged Isolation and Article 3

In A.B v. Russia, the court held that prolonged and unjustified separation within detention could amount to inhumane or degrading treatment, in violation of Article 3. The applicant in this case, ‘A.B.,’ was held for several years in near total separation from other detainees. The applicant had extremely limited human contact and no meaningful explanation of why this isolation was necessary. The court emphasized that the length and intensity of the isolation, and the lack of safeguards, were central to its finding of a violation of Article 3  (A.B. v. RUSSIA, 2021). 

The court also assessed the applicant's situation cumulatively. In particular,the court noted that prolonged isolation can cause serious psychological suffering, even if there was no physical abuse. Its ruling stressed the impact of mental health as a relevant factor in determining whether treatment reaches the Article 3 minimum level of severity (A.B. v. RUSSIA, 2021).Another important factor in the case was the absence of individualized justification and consistent review. The authorities failed to demonstrate why continued isolation was necessary in the applicant's specific circumstances, and there was no meaningful mechanism to assess whether these severe conditions were needed over time. The court treated this lack of procedural protection as integral to the Article 3 violation. 

B. S.D. v. Greece: Conditions of Detention and Arbitrary Confinement

Similarly, in S.D v. Greece, the European Court of Human Rights examined the detention of a migrant held in facilities for foreign nationals. The Plaintiff who was a Turkish Journalist who applied for asylum on July 12, 2007 was arrested and held in the Soufli holding facility for foreigners followed by the Petrou Rail Facility in Attica for unauthorized entry into Greece. Furthermore, the court held that the conditions of detention in the Soufli and Petrou Rali holding centers amounted to degrading treatment, violating Article 3, and the applicant's detention was unlawful and arbitrary under Article 5 §§ 1 and 4 due to the lack of an effective mechanism to challenge its lawfulness (S.D. v. Greece, 2009).  The court based its Article 3 finding on the conditions of the detention center. For approximately two months, the applicant was detained in a facility where he lacked access to the outdoors and was deprived of basic necessities such as blankets, clean bedding, hot water, and adequate hygiene products. He was confined in an overcrowded room, and he was later transferred to another holding facility where he was confined to his cell continuously for six days (S.D. v. Greece, 2009). 

Consequently, the court rejected the Government's argument in this case, which was that the detention was too brief to violate Article 3. The court held that even a relatively short period of detention can amount to degrading treatment when conditions are sufficiently severe. This ruling emphasized this especially because the applicant had documented physical and psychological injuries resulting from prior ill-treatment in Turkey and was detained without adequate medical care (S.D. v. Greece, 2009). As a result, the court deemed that this situation met the Article 3 threshold for degradation. The court also found a violation of Article 5 §§ 1 and 4 because the applicant was detained for the purpose of deportation at a time when deportation was legally suspended under Greek law due to his pending asylum application. Despite this, the authorities continued to detain him (S.D. v. Greece, 2009). Moreover, Greek law provided no effective procedure for the applicant to challenge the lawfulness of that detention. The court described this situation as a ‘legal vacuum’ in which detention persisted without substantive justification or judicial review (S.D. v. Greece, 2009). The absence of this prompt and effective review constituted an arbitrary and unlawful deprivation of liberty under Article 5. 

C. Lessons from European Jurisprudence

In S.D. v. Greece and A.B. v. Russia, the Court made clear that detention conditions must be assessed together. Extended separation from others, heavy restrictions on movement and contact, and the absence of clear justification or review can collectively amount to inhuman or degrading treatment under Article 3. When these conditions persist without proper oversight, detention may also violate Article 5.

V. U.S. Legal Framework for Civil Immigration Detention

A. Statutory Authority Under INA § 236(a)

The U.S. also has statutory and administrative laws that authorize civil immigration detention of non-citizens under  INA § 236(a) (8 U.S.C. § 1226(a)). This legal code permits the Department of Homeland Security (DHS), through Immigration and Customs Enforcement (ICE), to arrest and detain a non‑citizen who is “removable” pending a decision on whether they should be released on bond, granted conditional parole, or detained pending removal proceedings. The statute empowers the Attorney General, now delegated to the Department of Homeland Security and Immigration and Customs Enforcement, to make custody determinations, to set bonds, and to parole certain non‑citizens on conditions (8 U.S.C. § 1226(a); The Law of Immigration Detention: A Brief Introduction, 2025). The statute also authorizes discretionary alternatives to continued custody and does not make detention the default outcome, instead granting the government discretion to detain or release individuals pending removal proceedings (8 U.S.C. § 1226(a)). 

However, the statute does not provide procedural safeguards. In particular, INA §236 does not require the government to make an individualized finding that detention is necessary in each case, such as specific proof that the person is a flight risk or a danger to the community (Immigration Detention: A Legal Overview, 2025). It also does not set a fixed statutory maximum detention duration for civil immigration detainees under §236, and it does not guarantee the availability of a bond hearing within a set timeframe or require particular procedures for custody review beyond administrative rules (The Law of Immigration Detention: A Brief Introduction, 2025). As a result, while the statute authorizes release options, it leaves key questions—among them when is detention necessary, how long will it last, and what procedural safeguards apply—driven primarily by executive discretion rather than statutory command (Immigration Detention: A Legal Overview, 2025). 

Under §236(a), ICE has authority to set bond and parole in individual cases, and federal regulations and agency guidance implement the procedures for custody determinations, bond schedules, and review procedures (8 U.S.C. § 1226(a); Immigration Detention: A Legal Overview, 2025). These processes operate through administrative practice, but the statute itself does not provide a guaranteed right to release, a bond hearing within a fixed timeframe, or a defined evidentiary standard (The Law of Immigration Detention: A Brief Introduction, 2025). Importantly, the legal structure separates executive custody authority from judicial oversight. While immigration judges may review bond decisions within the administrative immigration system, §236(a) does not impose substantive statutory limits on the duration or intensity of detention (Immigration Detention: A Legal Overview, 2025). 

B. ICE Detention Standards and Oversight Gaps

ICE Detention standards, including the National Detention Standards (NDS) and the Performance-Based National Standards (PBNDS), regulate facility operations and detention practices through administrative guidance and through contracts (National Immigration Forum, 2025). These standards may shape agency practice through contract compliance, but they are not statutory law and do not carry the force of law. They do not create independent legal rights or change the detention authority granted by §236(a). Therefore, the detention standards reflect agency norms and contract expectations, but not binding statutory safeguards governing the legality of detention.  

Thus, §236(a) establishes a discretionary system of civil immigration detention. It authorizes the government to detain non-citizens during removal proceedings and to release them on bond or conditions, but it does not require individualized necessity determinations, impose statutory time limits, or mandate procedural safeguards beyond administrative review. These features of the statutory framework are central in assessing whether the use of prolonged or restrictive detention practices, such as solitary confinement, can result in arbitrary detention under international law.

VI. Solitary Confinement in Practice: Evidence from U.S. Case Law

U.S. case law addressing conditions of civil immigration detention is limited, and courts have rarely evaluated the use of solitary confinement directly. However, several cases describe how solitary confinement is used in practice within immigration detention facilities, particularly as a disciplinary tool.

A. Menocal v. GEO Group

In Menocal v. GEO Group (10th Cir. Oct. 22, 2024), civil immigration detainees held at the Aurora Immigration Processing Center in Colorado brought a class action against GEO Group, a private contractor operating the facility under contract with U.S Immigration and Customs Enforcement (Menocal v. GEO Group, 2025). Although the primary claims concerned forced labor under the Trafficking Victims Protection Act, the record also documented the practices and conditions at the facility. GEO Group required detainees to clean shared housing areas, including floors, bathrooms, and common spaces. The record also showed that detainees faced punishment if they refused to perform these tasks. They would lose basic privileges such as access to phones, televisions, and recreational activities, and if their refusal continued, penalties could escalate to solitary confinement. Several former detainees testified that officers threatened them with segregation, and some reported being placed in isolation. The district court cited evidence that detainees were sometimes held in solitary confinement for up to seventy-two hours for refusing to perform cleaning tasks (Menocal v. GEO Group, 2025). While the Tenth Circuit court did not rule on the lawfulness of these practices, this case documents the use of solitary confinement as a disciplinary measure within civil immigration detention.

B. Barrientos v. CoreCivic

A similar pattern appears in Barrientos v. CoreCivic, Inc. (11th Cir. Feb. 28, 2020), which involved detainees held at the Stewart Detention Center in Georgia. The facility is operated by CoreCivic, a private company working under contract with ICE. The detainees challenged how CoreCivic ran the facility’s ICE-approved “voluntary work program,” arguing that the program was coercive rather than truly voluntary (Barrientos v. CoreCivic, Inc, 2020).

The lawsuit alleged that detainees were pressured to participate in work assignments and faced negative consequences if they refused. According to the complaint, they were threatened with worse living conditions and disciplinary punishment (Barrientos v. CoreCivic, Inc, 2020). The complaint also alleged that solitary confinement, referred to by the court as “disciplinary segregation,” was threatened or used as part of work-related discipline. Namely, the plaintiff claimed he was placed in segregation for ten days after threatening to organize a work stoppage (Barrientos v. CoreCivic, Inc, 2020).

CoreCivic moved to dismiss the case, but the district court refused and certified a legal question for appeal, whether the Trafficking Victims Protection Act (TVPA) can apply to work programs in federal immigration detention facilities run by private, for-profit contractors (Barrientos v. CoreCivic, Inc, 2020). The Eleventh Circuit addressed only whether the TVPA could apply to private contractors operating immigration detention facilities and did not assess the legality of detention conditions or the use of segregation. As in Menocal, the court left unresolved whether solitary confinement was necessary, proportionate, or lawful in a civil detention context.

C. Serrabi v. United States

The same use of prolonged isolation is evident in Serrabi v. United States, a civil lawsuit filed in the U.S. District Court for the Middle District of Florida on November 22, 2024. The case was brought under the Federal Tort Claims Act by Guillermo Antonio De Leon Serrabi, who was detained by ICE at the Baker County Detention Center in Florida. According to the complaint, Serrabi filed an administrative claim with ICE, which was denied in May 2024, and he then filed this lawsuit within the required time period. The case is still at the complaint stage, and the court has not ruled on the claims (Serrabi v. United States, 2024).

Although Baker County Detention Center is a county-run facility, the complaint places responsibility on ICE. It alleges that ICE officers directed and supervised the actions that led to Serrabi’s confinement in segregation and that those officers were acting within their federal duties. The complaint asserts that when Serrabi was transferred back to Baker on October 29, 2021, he was placed in solitary confinement, and was kept there for about 88 days (Serrabi v. United States, 2024). ICE officers controlled both the decision to place him in segregation and the decision to keep him there. The complaint also alleges that Serrabi was told multiple times that he would remain in solitary confinement unless he agreed to sign documents related to his removal from the United States (Serrabi v. United States, 2024).

While in segregation, Serrabi alleges that he was denied phone calls, recreation, and contact with other detainees. The complaint states that officers repeatedly visited him to ask whether he would sign removal-related paperwork. It also describes an incident in December 2021 in which a correctional officer allegedly struck Serrabi in the ear, causing a ruptured eardrum and lasting hearing problems. According to the complaint, medical care after this incident was delayed and limited (Serrabi v. United States, 2024).

The complaint also described Serrabi's mental health concerns when he entered detention, given his status as a moderate risk. During the time he spent in segregation, the complaint claims that his mental health worsened. He experienced hallucinations, increased anxiety and depression, and suicidal thoughts. Serrabi alleges that he asked for medical and mental-health care during this period and that those requests were denied. The complaint also alleges that the required documentation and review were missing. According to the pleading, Serrabi’s file does not contain written segregation orders, regular reviews, or records showing individualized reasons for keeping him in isolation. ICE did not document required mental-health reviews, suicide-risk assessments, or follow-up reviews after the alleged use of force in December 2021 (Serrabi v. United States, 2024). Although the case remains pending, the record documents prolonged, unreviewed isolation within civil immigration detention and the serious harm that can result.

VII. Arbitrary Detention Under International Law: Application to the United States

Under international human rights law, detention becomes arbitrary not only when it lacks a legal basis, but when it is unnecessary, disproportionate, or carried out in a way that hurts human dignity (ICCPR art. 9; Human Rights Committee, General Comment No. 35). Article 9 of the ICCPR requires that deprivation of liberty be justified in the individual case and subject to meaningful review (ICCPR art. 9). Article 10 further requires that all detained individuals be treated with humanity and respect for their dignity (ICCPR art. 10). These standards apply regardless of whether detention is classified as civil or criminal (Human Rights Committee, General Comment No. 35). The evidence shows that U.S. immigration detention practices, particularly the use of solitary confinement, fail to meet these requirements (Cuffari, 2021; Physicians for Human Rights, 2025).

Although U.S. law authorizes civil immigration detention under INA § 236(a), that authority is framed broadly and leaves critical safeguards to executive discretion (Immigration Detention: A Legal Overview, 2025). The statute does not require the government to show that detention is actually necessary in each case, does not impose time limits, and does not guarantee prompt or effective review of restrictive conditions such as solitary confinement (The Law of Immigration Detention: A Brief Introduction, 2025). International law, however, makes clear that legality under domestic law is not enough (Human Rights Committee, General Comment No. 35). Detention may still be arbitrary if it is unjust, unpredictable, unnecessary, or disproportionate in practice (ICCPR art. 9).

Oversight findings show that ICE’s use of solitary confinement consistently lacks the individualized justification required under international law. The DHS Office of Inspector General found that ICE failed to document consideration of alternatives to segregation in the majority of cases and often did not even record segregation placements as required under its own policies (Cuffari, 2021). In more than 70% of reviewed cases, there was no evidence that ICE considered less restrictive measures before placing individuals in isolation, and reviews for prolonged segregation were frequently not conducted (Cuffari, 2021). These failures undermine the necessity and proportionality requirements under ICCPR Article 9 (ICCPR art. 9; Human Rights Committee, General Comment No. 35).

ICE is not limited to isolated failures, but instead reflects a structural pattern of systemic misconduct resulting in recurring violations of due process and civil rights. ICE detention standards describe segregation as a serious measure that should be used only as a last resort, especially for individuals with mental-health vulnerabilities (National Immigration Forum, 2025). Yet those standards are not legally binding, are unevenly applied across facilities, and carry little consequence when violated (National Immigration Forum, 2025). As the National Immigration Forum explains, detention standards operate largely as guidance rather than enforceable law, creating a system in which compliance depends on contract terms and internal discretion rather than legal obligation (National Immigration Forum, 2025). This weak system allows prolonged isolation to occur without meaningful legal restraint (Cuffari, 2021).

International law also requires that detention not expose individuals to serious harm (ICCPR art. 10). The Physicians for Human Rights report documents that solitary confinement in U.S. immigration detention is used extensively, often for weeks or months, and frequently against people with known medical or mental-health vulnerabilities. The report shows that prolonged isolation causes severe psychological harm, including hallucinations, suicidal ideation, and lasting trauma, and that ICE continues to use solitary confinement despite well-documented risks and international condemnation of the practice (Physicians for Human Rights, 2025). Under Article 10 of the ICCPR, detention that predictably causes such harm cannot be considered humane (ICCPR art. 10).

The use of solitary confinement as a tool of control or coercion further supports a finding of arbitrariness in U.S. immigration detention. Documentation from detention facilities shows that isolation is frequently used in response to behavior that does not pose a genuine safety threat, including rule violations, refusal to comply with staff demands, or requests for basic needs (Cuffari, 2021; Physicians for Human Rights, 2025). The pattern described in multiple reports where segregation is used to punish, pressure, or silence detainees conflicts with the civil nature of immigration detention and mirrors punitive practices (Cuffari, 2021; Physicians for Human Rights, 2025; Immigrant Accountability Project, 2024). Detention used in this way exceeds what is necessary to ensure appearance at immigration proceedings and, therefore, fails the proportionality requirement under international law (ICCPR art. 9).

Evidence of failed oversight at facilities like Eloy Detention Center demonstrates how detention becomes arbitrary when accountability fails. The record of deaths, suicides, medical neglect, and use of segregation at Eloy demonstrates how prolonged isolation operates within an already harmful detention environment (Immigrant Accountability Project, 2024). Despite repeated documentation of abuse and systemic failures, ICE has continued to operate the facility and extend its contracts, reflecting a lack of effective accountability or corrective action (Immigrant Accountability Project, 2024). When detention conditions reach this level of severity and persist without meaningful reform, continued confinement loses any claim to legitimacy under international standards (ICCPR arts. 9–10).

Thus, U.S. law and practice allow a form of civil immigration detention in which individuals may be placed in prolonged solitary confinement without individualized necessity determinations, without enforceable limits, and without effective review. The consistent failure to consider alternatives, document justification, protect vulnerable individuals, and prevent serious harm shows that solitary confinement is not used as an exceptional measure but as a routine management tool (Cuffari, 2021). Under ICCPR Articles 9 and 10, detention carried out in this manner is arbitrary because it is unnecessary, disproportionate, and incompatible with the requirement of humane treatment (ICCPR arts. 9-10).

VIII. Government Justifications and International Law Responses

The U.S. government could argue that immigration detention, including the use of segregation, is lawful because it is authorized under domestic law and classified as civil rather than criminal (Heartland Alliance’s National Immigrant Justice Center (NIJC) and Physicians for Human Rights (PHR, 2012). From this perspective, the government may argue that solitary confinement does not automatically violate international law so long as detention itself is lawful and segregation is framed as administrative, protective, or necessary to manage large detention populations. This argument relies heavily on the formal legality of detention under INA § 236(a) and on the government’s discretion to manage detention facilities during periods of large numbers of migrants arriving at American borders.

International law, however, rejects the idea that formal legality alone is sufficient. The Human Rights Committee has been explicit that arbitrariness includes detention that is unjust, unnecessary, disproportionate, or insufficiently reviewed. This means the relevant question is not whether the United States has the legal authority to detain migrants, but whether detention and especially restrictive measures like solitary confinement are justified in each individual case. When solitary confinement is enforced without individualized reasons, clear necessity, or meaningful review, detention becomes arbitrary regardless of its civil classification.

In addition, the government may argue that solitary confinement in immigration detention does not violate human rights because detention is civil and segregation is used for safety or operational purposes (Heartland Alliance’s National Immigrant Justice Center (NIJC) and Physicians for Human Rights (PHR, 2012). This overlooks an important element of international law: the distinction between the legality and the conditions of detention. Even when detention is lawful under Article 9, the conditions of confinement must still comply with Article 10 of the ICCPR and Article 3 of the European Convention, which prohibit inhumane or degrading treatment.

European Court of Human Rights case law is especially clear on this point. In cases such as A.B. v. Russia and S.D. v. Greece, the Court did not require proof of criminal punishment or physical abuse to find violations. Instead, it examined whether isolation was necessary, how long it lasted, whether it was justified in the individual’s circumstances, and whether authorities provided safeguards and review. The Court held that prolonged or severe isolation can, on its own, violate Article 3, and that detention may simultaneously violate Article 5 when it lacks proper justification or review. International law requires this distinction, with Article 9 addressing whether detention is arbitrary and Article 10 addressing how detained individuals are treated.

The U.S. government may also face unique migration pressures and operational constraints, including overcrowding, staffing shortages, and limited detention capacity. While international law recognizes that states face practical challenges in managing migration, it does not permit states to shift the burden of those failures onto detained individuals. Both the Human Rights Committee and the European Court have rejected resource constraints as a justification for degrading treatment or arbitrary detention. In S.D. v. Greece, the Court held that even short-term immigration detention can violate Article 3 when conditions are severe, and it made clear that administrative difficulty or overcrowding does not excuse inhuman or degrading treatment.

Solitary confinement is argued to be used “appropriately” in immigration detention, but that assertion does not resolve the arbitrariness question. International law does not assess practices in the abstract—it assesses how they are used in reality. The record in the United States documented by oversight reports, medical experts, and litigation shows that solitary confinement is routinely used without individualized justification, often for prolonged periods, and frequently against people with known vulnerabilities. When a restrictive measure is used in this manner, it's not exceptional and becomes systemic. Detention no longer satisfies the requirements of necessity and proportionality under Article 9, and the conditions of confinement fail to meet the humanity and dignity required under Article 10.

IX. Oversight and Accountability: U.S. and European Comparison

These patterns persist in part because of how immigration detention is overseen. In the U.S., detention standards are not legally binding, and oversight is largely internal. Inspections are conducted by or on behalf of DHS, and even when serious violations are documented, detention facilities are often not legally required to change their practices. Judicial review of detention conditions is also limited, leaving little external scrutiny of whether restrictive measures such as solitary confinement are necessary or proportionate in individual cases (National Immigration Forum, 2025).

By contrast, European detention systems operate within an external oversight system. The European Committee for the Prevention of Torture (CPT) conducts unannounced inspections of immigration detention facilities as an independent monitoring body, and its findings are publicly reported (European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment (CPT), 2014). CPT reports are frequently relied upon in proceedings before the European Court of Human Rights, and when the Court finds a violation of the European Convention, those judgments are binding on states under Article 46 (European Committee for the Prevention of Torture and Inhuman or Degrading Treatment or Punishment (CPT) CPT Standards “Substantive” Sections of the CPT’s General Reports, n.d.). This structure does not eliminate abuse, but it creates enforceable pressure to justify detention practices and to correct violations when they occur. The absence of external and binding oversight in the U.S. system reinforces the risk that solitary confinement will be enforced without the safeguards required under international law.

European systems also face migration pressures and detention-related problems, but European courts have made clear that administrative difficulty or lack of capacity does not excuse violations of fundamental rights. European case law shows how international standards are applied in practice. In contrast, the absence of binding detention standards and external oversight in the United States allows solitary confinement to be used with little accountability. Thus, U.S. law permits a system in which civil immigration detention can operate arbitrarily, in violation of ICCPR Articles 9 and 10. 

X. Recommendations for Compliance with International Law

To bring U.S. immigration detention practices into compliance with international human rights standards, several reforms are necessary. First, the use of solitary confinement in civil immigration detention should be limited through binding rules. Segregation should be used only as a last resort, for the shortest time possible, and only when there is a clear and individualized safety need. Prolonged isolation, especially for people with mental-health conditions, should be prohibited. Further, meaningful procedural safeguards must accompany any use of segregation. This includes written justification for placement, documented consideration of less restrictive alternatives, prompt review by an independent decision-maker, and regular reassessment of continued confinement. Without enforceable review mechanisms, detention decisions cannot meet the necessity and proportionality requirements under international law. Thus,oversight of immigration detention must extend beyond internal agency monitoring. Independent external inspection mechanisms should be strengthened, and findings of serious violations should carry enforceable consequences. Increased judicial oversight of detention conditions would further help ensure that civil detention does not move into punitive confinement without accountability.

Finally, the United States should reaffirm its obligations under the ICCPR by aligning domestic detention practices with international standards governing deprivation of liberty and humane treatment. Immigration detention systems that rely on prolonged isolation without justification or effective review undermine both human dignity and the rule of law. Addressing these practices is necessary not only to comply with international legal obligations, but to ensure that civil immigration detention proceedings do not operate as a form of arbitrary punishment.

XI. Conclusion

The routine use of solitary confinement in U.S. civil immigration detention cannot be reconciled with international human rights law. Although U.S. law authorizes immigration detention as a civil measure, international standards require that any deprivation of liberty be necessary, proportionate, and subject to meaningful review. The cases examined demonstrate that solitary confinement is frequently imposed without individualized justification, enforceable limits, or effective oversight, and often results in serious mental and physical harm. European case law interpreting Articles 3 and 5 of the European Convention on Human Rights asserts that prolonged or severe isolation, especially when unreviewed, can amount to inhuman or degrading treatment and render detention arbitrary. When applied to U.S. practices, these standards make clear that prolonged solitary confinement in civil immigration detention violates Articles 9 and 10 of the ICCPR. Without binding safeguards, external oversight, and meaningful review, the continued use of solitary confinement undermines both the civil character of immigration detention and the United States’ obligations under international law.