It would have been among the most important criminal trials in American history: the prosecution of accused 9/11 mastermind Khalid Sheikh Mohammed (KSM). But instead, KSM, along with his four alleged co-conspirators, remain in legal limbo at Guantanamo, two decades after U.S. officials took them into custody. Congress has blocked bringing any Guantanamo detainee into the United States, even for criminal trial, despite the fact that federal prosecutors of alleged terrorists have obtained nearly 700 convictions since 9/11, including in numerous high-profile cases. Meanwhile, Guantanamo’s military commissions, where KSM and his co-defendants face charges for war crimes and terrorism, remain stymied in controversy, with no trial date in sight. It is thus distinctly possible that the person primarily responsible for the murder of nearly 3,000 individuals and the worst terrorist attack in U.S. history (and who is now nearing 60 years of age) will die in prison without ever being convicted of a crime.

There still remains, however, one viable avenue for resolving the 9/11 case that, if not a vindication of justice (words that can never attach to Guantanamo), could provide at least some rough approximation of it.

The U.S. government has for years been engaged in plea negotiations with the 9/11 defendants (and has successfully concluded plea deals with other defendants in the military commissions, as discussed below). The central feature of any plea deal would be an admission of guilt by the defendants in exchange for a sentence of life imprisonment, thus avoiding imposition of the death penalty. Although the Trump administration scuttled the negotiations, the Biden administration has resumed them in earnest. Last month, the military judge in the 9/11 case cancelled all pre-trial hearings to await the Biden administration’s response on certain key issues central to a plea agreement.

Pleas are a dominant feature of the U.S. criminal justice system (approximately 97% per cent of federal felony prosecutions end in guilty pleas; the figure is only slightly lower for state felony prosecutions). Pleas offer benefits to all sides: for prosecutors, they minimize the burden and costs of litigation, avoid the possibility of acquittal, and help foster cooperation; for defendants, pleas similarly mitigate the risks of going to trial and offer the prospect of a more lenient sentence; and for victims, the plea process can further transparency and truth through mechanisms like stipulations of fact and, potentially, the opportunity for victims to pose questions to the defendants that they would be required to answer. Colleen Kelly, whose brother died on 9/11, pressed this point in her testimony to the Senate Judiciary Committee late last year, telling Members that she strongly supported pleas in no small part because the process could afford at least a chance “to finally get … answers to our questions about 9/11 from the defendants—answers and information that we have been denied for two decades.”

For these reasons, pleas have played in an increasingly important role at Guantanamo. In twenty-plus years of military commissions at Guantanamo, there have been only 10 convictions, and eight of those have been achieved through plea agreements.

Two factors underscore the particular utility of pleas at Guantanamo. First, the Guantanamo military commissions, which were initially designed to avoid procedural safeguards and other legal constraints, continue to suffer from shortcomings and questions about their legitimacy despite numerous rounds of reform. Plea agreements are a way to avoid deciding critical, unanswered questions surrounding the commissions, including the use of evidence obtained through torture and lesser forms of coercion, the legal validity of several war crimes charges (which turn, for example, on when the armed conflict with al Qaeda started), and the application of certain provisions of the Constitution itself, including the Sixth Amendment’s Confrontation Clause, which the government has long contested. Indeed, torture, which Brigadier General John G. Baker, the longtime Chief Defense Counsel for the military commissions, called the commission’s “original sin,” hangs over virtually every aspect of the commissions, infecting and providing grounds for invalidating any guilty verdict and capital sentence. To take one example: in the case of Abd Al-Rahim Al-Nashiri, who has been charged in the military commissions for his role in the attacks on the USS Cole and the MV Limburg, prosecutors have recklessly embraced evidence obtained through torture in violation of federal and international law and then “tied themselves in legal knots” trying to justify it, as Scott Roehm has described here. At minimum, any trial that decides the array of high-stakes issues presented by the 9/11 case will generate multiple and lengthy appeals, thus delaying, if not preventing, finality.

Second, military commission judges have demonstrated an ability to impose punishment while acknowledging the torture and other abuses the defendants experienced in U.S. custody. In the case of Majid Khan, who had been tortured at a CIA “black site,” seven (of the eight) members of the military jury found that the U.S. government’s treatment of Khan had shown “complete disregard for the foundational concepts upon which the Constitution was founded” and urged clemency. The Convening Authority for military commissions reduced Khan’s sentence from 26 to 10 years. (Of course, that decision is only meaningful if Kahn, who continues to be detained seven months after completing his sentence, is promptly released).

The sheer magnitude of the 9/11 defendants’ alleged crimes might seem to outweigh the rationale for the clemency provided to Khan (while Khan admitted to serving as a courier for al Qaeda, he, unlike KSM and his co-defendants, had no direct role in the 9/11 attacks). But there are several reasons why a plea deal is still merited in the 9/11 case.

First, a plea deal for the 9/11 defendants that avoids the death penalty in exchange for life imprisonment can be justified on other grounds. On a practical level, it would avoid what would otherwise be more protracted litigation, including at the sentencing phase of a military commission trial, where defendants would argue that their torture is a mitigating factor precluding a capital sentence. And, given what happened in Khan, it is possible that after hearing about the defendants’ gruesome treatment in U.S. custody, the military jury might ultimately recommend life imprisonment rather than the death penalty for some or even all of the 9/11 defendants. But even if not, two things are certain: a death sentence will face a rocky road on appeal and the appeals will take years to resolve (that is, assuming a trial ever takes place).

Second, the death penalty for any of the 9/11 defendants would  mean there is no legal consequence for the torture that was sanctioned at the highest levels of the U.S. government. As Justice Robert H. Jackson, the chief U.S. prosecutor at Nuremberg, explained, the premise of putting those who commit atrocities on trial is to submit them to the judgment of law. Just as it is important to hold the perpetrators of 9/11 criminally responsible, so too is it important to acknowledge—in a way with actual legal consequence—the massive crimes that the U.S. government perpetrated in response—crimes, moreover, that were as indiscriminate as they were brutal, sweeping in many innocent people. The prosecution of the 9/11 defendants provides a unique opportunity to do so.

Third, and most importantly, the U.S. owes it to the families of the victims of the 9/11 attacks to bring finality after an inexcusable delay. Indeed, a number of victims’ family members support final resolution of the 9/11 case through a plea agreement, even if it means foregoing a death sentence (this support, to be sure, is not universal and other victims’ family members oppose any such agreement). Family members, moreover, will be able to testify at sentencing—an opportunity they will be denied if the case never goes to trial.

In considering this trade-off, it is important to remember that the United States bears full responsibility for the unconscionable delay and continuing legal morass. After capturing KSM in 2003, the U.S government chose to disappear him in a secret CIA prison where it repeatedly tortured him (including by waterboarding him over 180 times). Then, when the Supreme Court effectively confirmed that CIA black sites were unlawful in 2006 by ruling in Hamdan v. Rumsfeld that Common Article 3 of the Geneva Conventions applied to the armed conflict with al Qaeda, the Bush administration chose to transfer KSM and his co-defendants to Guantanamo, effectively doubling down on the off-shore prison and their fatally flawed military commissions. And in 2010, President Obama abandoned his plan to bring the 9/11 defendants to federal court to face charges (and a possible capital sentence) in the face of a political backlash. Had the defendants been brought to federal court, it is almost certain that the 9/11 case would have been resolved years ago.

Resolving the case of the 9/11 defendants—the only individuals at Guantanamo accused of a direct role in the 9/11 attacks—will remove one of the remaining obstacles to closing Guantanamo and render its continued existence even more absurd. At that point, all that remains will be to resolve the handful of other military commission cases and transfer the other remaining prisoners—20 of whom the U.S. government has already cleared for release—to other countries.

Global events in the past year have made it more imperative to resolve the 9/11 case. The U.S. government is rightly backing various efforts to hold Russia accountable for its aggression and war crimes in Ukraine, including at the International Criminal Court, which the United States has still refused to join and has undermined in the past. U.S. critiques of Russia have highlighted America’s own selective fidelity to international norms in the past, from its invasion of Iraq (see Kevin Jon Heller’s post here) to its torture of detainees in the War on Terrorism (see Joe Margulies’ post here). It is likewise deeply problematic that the United States has still failed to try the 9/11 defendants after twenty years. At a time when the United States (and its allies) are stressing the need to hold Russia accountable for war crimes, the United States should finally resolve the single most important 9/11 case in a way that demonstrates at least some regard for the international norms it trumpets when it serves its strategic interests.

IMAGE: Razor wire tops the fence of the U.S. prison at Guantanamo Bay, also known as “Gitmo” on October 23, 2016 at the U.S. Naval Station at Guantanamo Bay, Cuba. (Photo by John Moore/Getty Images)