The Evidentiary Question at Guantanamo Bay

Habeas corpus is often described as a fundamental liberty in the American legal system. At its center lies a simple demand: the government must justify its holding of an individual. Yet the post 9/11 detention regime revealed just how fragile that promise becomes when law begins to operate under conditions of fear. At Guantanamo Bay, a U.S. naval base in Cuba turned detention center after the devastating attacks on September 11, individuals were held not based on established legal responsibility or reliable evidence, but on unverified suspicion, much of which was produced through coercive interrogation methods. Rather than suspending habeas corpus outright, the post 9/11 detention system hollowed it out by lowering the standards of proof in order to place detainees beyond the full reach of constitutional protections and to limit the application of international law, leaving many held indefinitely with little to no access to legal counsel. 

This crisis of evidence reveals how far the U.S. departed from the rule of law in the post 9/11 legal system, where suspicion replaced proof. Detention was no longer based on evidence that could withstand scrutiny, but instead on uncertainty and intelligence that was not often tested. By lowering evidentiary standards and leaving claims unchecked, the detention system became easier to sustain and harder to challenge. Habeas corpus remained formally available, but it operated under constraints that limited its ability to meaningfully test the government’s case. This paper argues that the central issue at Guantanamo was not the absence of legal process, but the erosion of evidentiary standards that made that process ineffective. In this way, law appeared to constrain executive power, but only at the margins, ultimately allowing a system built on weak and unreliable evidence to persist. 

This evidentiary shift did not happen by accident. It took shape in the months following September 11, when the U.S. purposely placed suspects outside the ordinary criminal justice process and sought to limit the application of international legal protections by transferring them to Guantanamo Bay. President George W. Bush’s military order of November 13, 2001, authorized detention solely on “reason to believe” and explicitly barred detainees from seeking “any remedy… in any court of the United States.” The executive thereby created a legal ‘grey’ category, framing detention as a form of law-of-war detention under the Authorization for Use of Military Force and applying the label of “unlawful enemy combatant.” This allowed for a bypass of normal judicial scrutiny and a lowering of the burden of proof required to justify detention. 

The move made in Bush’s military order was subtle, as detainees’ rights were not outright denied but made unreachable. As international law scholar and former war crimes prosecutor Leila Sadat puts it, detainees were subject to a “régime d’exception - an extraordinary regime created de novo by the Executive branch - in which any protections afforded the suspects become simply a matter of grace” (Sadat p. 539). This meant that detention decisions were made and reviewed within executive and military structures, with little to no access to independent courts and no requirement to meet standard evidentiary rules. While the law remained intact, its protective force was essentially absent. 

When the Supreme Court finally intervened in Boumediene v. Bush, 553 U.S. 723 (2008), it seemed to have corrected this power imbalance. The Court ruled that detainees at Guantanamo had a constitutional right to habeas corpus and made note that judicial review must be “meaningful.” At first glance, this marked a reassertion of the rule of law. But habeas corpus requires more than access to a court: it requires that the government justify detention with sufficient and reliable evidence before an independent judge. The purpose of habeas review is to test the factual basis of detention, not simply to confirm its existence.  

At Guantanamo, that expectation was not upheld. While the right to challenge detention technically existed, courts in cases such as Boumediene v. Bush and Parhat, Huzaifa v. Gates, Robert, No. 06-1397 (D.C. Cir. 2008), were often forced to assess detention based on evidence derived from coercive interrogation practices, including sleep deprivation, stress positions, and prolonged isolation. These methods, widely criticized and in some cases found to violate both U.S. and international legal standards, produced statements that were unreliable and often secondhand. Despite this, such intelligence continued to be used in habeas proceedings, even though it would be inadmissible in ordinary criminal trials. As a result, habeas corpus functioned more as a procedural formality than as a constitutional protection used to meaningfully test the government’s claims. 

The main failure of the Guantanamo detention system was not only that detainees were held indefinitely, but that the evidence used to justify their detention was unreliable. In many cases, the allegations against detainees were created from statements obtained through torture or coercive interrogation practices. Under U.S. law, evidence obtained through coercion or torture is inadmissible in criminal proceedings due to its unreliability and its violation of due process, Brown v. Mississippi, 297 U.S. 278 (1936). This principle is also seen in international law, which prohibits the use of statements obtained through torture as evidence (Convention Against Torture, art. 15). Criminal proceedings require that guilt is established beyond a reasonable doubt through evidence tested before an independent court. By contrast, the Guantanamo detention system operated outside of these rules, relying on intelligence and suspicion rather than proof beyond a reasonable doubt. Due to this, many detainees could not be prosecuted in criminal courts and were instead held under a system of preventive or law-of-war detention. 

Investigations later went on to confirm just how much abusive interrogation practices were being used to shape evidence. An inquiry made by the U.S. Senate found that the treatment of detainees in various facilities involved methods that raised “serious legal and ethical concerns,” which called into question the credibility of the intelligence gathered (Inquiry Into the Treatment of Detainees in U.S. Custody, p. xviii). Instead of seeking the truth, detainees gave in to compliance and the statements were not based on fact but instead made out of fear. Despite this, torture-tainted intelligence continued to play a main role in habeas proceedings. Courts were assessing whether detention was justified based on evidence that often relied on secondhand reports or coerced confessions. One study of Department of Defense data revealed that many detainees were held on “weak, secondhand, or corrupt evidence,” with a large number having no confirmed connection to al-Qaeda or the Taliban at all (Report on Guantánamo Detainees).   

This dynamic was not a paradox but a structural feature of the detention system. Because much of the evidence against detainees would have been inadmissible in criminal trials, it could not support prosecution. Instead, it was used to justify continued detention under a looser evidentiary framework. While judges acknowledged that statements obtained through coercion would not meet criminal standards, they nonetheless relied on such material (Hafetz). So, rather than excluding coerced-derived material, courts would defer to executive claims of national security to sustain a threshold of suspicion. In practice, this meant that habeas corpus rarely resulted in release. Even when judges would describe the government’s evidence as unreliable and unsupported, detainees often stayed trapped within an unjust, unchallenged detention system (Parhat, Huzaifa v. Gates, Robert).   

When the Supreme Court decided on Boumediene v. Bush, it seemed to mark a turning point in post 9/11 detention policy. The case was brought by detainees held at Guantanamo who challenged the Military Commissions Act, which had stripped them of the right to seek habeas corpus in U.S. courts. At stake was whether the executive had the power to place individuals beyond the reach of judicial review. The Court ultimately held that detainees at Guantanamo had a constitutional right to habeas corpus and rejected the government’s attempt to place Guantanamo outside of judicial reach. Justice Kennedy made clear that habeas review must be “meaningful” and capable of testing the factual basis for detention. This decision essentially restored the judiciary’s role as a check on the power of the executive. Yet, this case left much of the detention system intact. While habeas corpus is designed to guarantee access to judicial review, access alone proved insufficient in this context. The Court did not confront the lowered evidentiary standards which were governing detention, leaving detainees to challenge their confinement within a system that still permitted reliance on unsupported claims and evidence. As a result, lower courts were left to apply habeas review in a system where the rules were largely set by the executive. This meant that courts often accepted hearsay and referred to government claims about national security rather than applying the stricter evidentiary standards that normally govern the deprivation of liberty or the protections recognized under international law. 

This problem is seen in post-Boumediene litigation. While detainees could technically challenge the basis of their detention, courts were accepting false reports and hearsay, as habeas proceedings allowed for secondhand information. Therefore, habeas began to function more as a procedural task rather than a constitutional safeguard capable of dismantling a detention regime such as this one. So, while the Boumediene case initially seemed like a win for those held under false assumptions, it ultimately mattered more symbolically by rejecting the idea that the executive could go unchecked by the judiciary. However, symbolism is not the same as effectiveness. In practice, the decision did little to change how detention was justified: courts continued to rely on poor evidence, and the underlying evidentiary standards governing detention stayed mostly intact. As a result, detainees gained access to courts but not to a meaningful challenge of their detention. So, while this decision affirmed the existence of rights, it did not equip courts with the necessary tools to uphold them, as judges still had to assess detention based on thin evidence without strict evidentiary standards. 

Most scholarly debate over the question of Guantanamo revolves around whether judicial intervention actually put a check on executive power, or if it merely reshaped it. Adam R. Pearlman, national security law expert, gives a more optimistic interpretation in his “Meaningful Review and Process Due: How Guantánamo Detention Is Changing the Battlefield” (2015). His main argument is that Supreme Court intervention, particularly in Boumediene, brought accountability to wartime detention: “the existence of review processes has altered the conduct of detention operations by bringing legal accountability to the battlefield” (Pearlman 292). For Pearlman, the recognition of detainees’ right to “meaningful review” was a sign that the United States had not abandoned the rule of law in this time of crisis. He suggested that judicial oversight forced the executive to anticipate legal scrutiny and to slowly adapt its detention policies. This view makes habeas corpus evidence of legal resilience. From Pearlman’s perspective, procedures like habeas litigation and review boards prove that law can adjust to a crisis without falling completely into the discretion of the executive. By viewing law as something flexible and adaptable, he brings a tone of hopefulness to his piece, though his optimism is limited by the scope in which he assesses the law and how it changes. Pearlman measures progress through procedural change, arguing that increased oversight will slowly reshape detention practices over time. But this emphasis on gradual improvement overlooks the immediate reality that detainees continued to be held on insufficient evidence. Oversight reforms like review boards were often criticized as ineffective and largely symbolic, especially in the short term. As Human Rights Watch observed, “The tribunals are seriously flawed. They are not set up to be impartial; they will place severe limits on detainees’ ability to make their claims” (“U.S.: Review Panels No Fix for Guantanamo”). This suggests that, even if procedural changes may lead to gradual improvements over time, they did little to alter the immediate conditions of detention. Thus, the existence of oversight did not necessarily translate into meaningful protection, allowing the system to appear lawful without substantially addressing its underlying flaws. 

Leila Nadya Sadat, on the other hand, reaches the opposite conclusion. She claims that the post 9/11 legal framework did not restore rights, but normalized their suspension instead. The category of “unlawful enemy combatant,” she argues, has no basis in international law and was “employed to suggest that the prisoners captured in this ‘war’ are not entitled to ‘normal’ legal protections, but should instead be subjected to a régime d'exception,” (Sadat p. 539). In other words, the government built a separate legal system designed to operate outside traditional rights frameworks. Sadat writes that this legal framework effectively dehumanizes “a whole category of human beings” by placing them “in a presumption of guilt applicable to anyone accused of acts of terrorism by the government” (Sadat 541). For her, the post 9/11 system was not legal adaptation but legal distortion—a deliberate skewing of the law to serve executive agendas.  

Sadat also points out that even the Supreme Court’s later rulings, like Boumediene v. Bush, didn’t challenge the core of this post 9/11 detention system. While the Court allowed detainees to contest their detention, it “did not question the legitimacy of the classification scheme in the first place,” meaning that the structure of exclusion remained stagnant (Sadat 540). What the U.S. called reform was, in Sadat’s view, a way to make exceptional power appear legal. By creating a category of people who existed outside both civilian and military law, the government was able to blur the line between legal accountability and discretion. 

Through both authors, a central issue of Guantanamo jurisprudence becomes apparent. Habeas  corpus made it so that the executive could not operate in complete secrecy, but it didn’t require the government to meet normal standards of proof in criminal cases. Law constrained power more on the surface than in practice; it helped to legitimize a system that was built on suspicion  and a vague, large net cast by President George W. Bush in his Executive Order. In this way, Guantanamo shows how rights can survive formally while being emptied of their legal force.   

Guantanamo Bay is often regarded as an exceptional response to an exceptional situation. But the legal dynamics of this situation are neither temporary nor confined to Guantanamo Bay; they present a broader shift in how the U.S. uses law to manage perceived threats, extending into immigration detention and emergency governance. Law was not abandoned in the post 9/11 era; it was stretched and abused. While habeas corpus survived on paper, it operated within a system that essentially froze all its protective legal force. Detention was given without reliable evidence, and suspicion was enough of a justification for prolonged confinement. Even though judicial review gave some sense of legality, the evidentiary foundations of detention were never confronted, placing habeas review in sight but out of reach of those who needed it the most.   

The scholarly debate between authors like Pearlman and Sadat shows the same issue: law can constrain power at the margins while still legitimizing its excesses. By focusing on procedure, courts affirmed rights without ensuring that they would be effective in practice. Guantanamo thus stands as a warning about how easily legal protections can begin to dismantle even when they are formally upheld.  

The lessons from Guantanamo are not just confined to the past. As contemporary debates over immigration and access to habeas corpus continue in the U.S., Guantanamo reminds us that the more serious threats to our rights don’t always come from their outright suspension, but from their quiet diminishing. When legality no longer cares for or demands proof, the rule of law risks becoming a performance rather than a safeguard.

Works Cited

Boumediene v. Bush, 553 U.S. 723 (2008)  

Brown v. Mississippi, 297 U.S. 278 (1936) 

COMMITIEE ON ARMED SERVICES. Inquiry into the treatment of detainees in U.S. custody |United States Senate Committee on Armed Services. Accessed November 29, 2025. https://www.armed-services.senate.gov/download/inquiry-into-the-treatment-of detainees-in-us-custody.  

Convention against torture and other cruel, inhuman or degrading treatment or punishment. OHCHR. (n.d.). https://www.ohchr.org/en/instruments-mechanisms/instruments/convention-against-torture-and-other-cruel-inhuman-or-degrading  

Denbeaux, Mark and Denbeaux, Joshua W. and Gregorek, John Walter, Report on Guantanamo Detainees: A Profile of 517 Detainees Through Analysis of Department of Defense Data (February 2006). Seton Hall Public Law Research Paper No. 46, Available at SSRN: https://ssrn.com/abstract=885659  or http://dx.doi.org/10.2139/ssrn.885659   

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Hafetz, Jonathan (2007) "Guantanamo and the "Next Frontier" of Detainee Issues," Seton Hall Law Review: Vol. 37 : Iss. 3 , Article 4. Available at: https://scholarship.shu.edu/shlr/vol37/iss3/4   

Huzaifa Parhat, Petitioner v. Robert M. Gates, Secretary of Defense, et al., Respondents, No. 06-1397, United States Court of Appeals for the District of Columbia Circuit, 20 June 2008, https://www.refworld.org/jurisprudence/caselaw/usacadc/2008/en/60665   

Office of the Federal Register, National Archives and Records Administration. Public Law 107 - 40 - Authorization for Use of Military Force. U.S. Government Printing Office, (18 Sept. 2001), https://www.govinfo.gov/app/details/PLAW-107publ40  

Pearlman, Adam R., Meaningful Review and Process Due: How Guantanamo Detention Is Changing the Battlefield (February 4, 2015). Harvard National Security Journal, Volume 6, 2015, Available at SSRN: https://ssrn.com/abstract=2560152  

Parhat, Huzaifa v. Gates, Robert, No. 06-1397 (D.C. Cir. 2008) 

Sadat, Leila N., A Presumption of Guilt: The Unlawful Enemy Combatant and the U.S. War on Terror (2009). 37 Denver Journal of International Law and Policy 539, 2009, Washington University in St. Louis Legal Studies Research Paper No. 20.03.04, Available at SSRN: https://ssrn.com/abstract=3549566  

“U.S.: Review Panels No Fix for Guantanamo.” Human Rights Watch, July 27, 2004. https://www.hrw.org/news/2004/07/27/us-review-panels-no-fix-guantanamo.