When a federal judge ordered the release of 17 Guantánamo Bay detainees earlier this month, it was the first real chance in the seven-year history of the prison camp that any of the prisoners might be transferred to the United States. In making his ruling, the judge categorically rejected the Bush administration's claim that any of the released prisoners, who are all Chinese Muslims, were "enemy combatants" or posed a risk to U.S. security. The decision was temporarily suspended by the appeals court, but the judge was on solid ground.

Controversy over the Bush administration's policy to detain enemy combatants at Guantánamo has raged since the facility opened in 2002--fueled primarily by the lack of legal protections afforded the detainees and allegations of their mistreatment. Often overlooked, however, is the fact that most of these detainees have never posed any real risk to America, for the simple reason that the vast majority of them were never "enemy combatants" in the first place. Indeed, striking new data we have obtained show that, if anything, the 17 innocent Chinese men are far from exceptional.

Before we get to the new statistics corroborating this startling fact, a quick review of how the detainees got to Guantánamo in the first place is helpful. Given the fog of propaganda surrounding the Guantánamo prisoners--whom former Secretary of Defense Donald Rumsfeld once famously described as "the worst of the worst"--you might be surprised to learn that, according to the Pentagon itself, only 5 percent of detainees at the prison were ever apprehended by U.S. forces to begin with. And only another 4 percent were ever alleged to have actually been fighting at all.

Why is that? Almost all of the detainees were turned over to U.S. forces by foreigners, either with an ax to grind or, more often, for a hefty bounty or reward. After U.S. forces invaded Afghanistan in late 2001, they doled out rewards of about $5,000 or more to Pakistanis and Afghans for each detainee turned over. Contrary to standard law enforcement practice, the U.S. military accepted the uncorroborated allegations of the award claimants with little independent investigation.

Now, under much pressure, the Pentagon has released more than 500 detainees over the past three years, while some 270 remain. Based on statistics about the fate of other released prisoners in other contexts, it would not have been surprising if many of these men had resumed their lives of terrorist crimes and illegal warfare. In the United States, more than two thirds of state prisoners are rearrested for serious new crimes within three years, according to the Department of Justice.

Terrorists are criminals too--indeed, ideologically committed ones. Every reasonable expectation would lead to the conclusion that the rate of recidivism for terrorists should be as high as, if not higher than, it is for other criminals. But guess what happened to the more than 500 terrorist detainees that the United States has released during the last three years? Only a handful has gone back to terrorism or the battlefield.

Almost a quarter of the Guantánamo detainees who have been released have been sent back to Saudi Arabia. Facing a substantial threat from terrorism in their own country, the Saudi authorities have been rigorous--some might say harsh--in imprisoning and punishing any terrorist deemed a danger. Yet in new statistics provided to us by the Ministry of Interior in Riyadh, zero of the 121 Guantánamo detainees received by the Saudis were deemed dangerous and ineligible for release.

It gets worse. Of those detainees returned to Saudi Arabia from Guantánamo, more than half have been released and are now free, most after spending a period of time in a halfway house designed to promote a smooth return to society. Only six former Guantánamo detainees have been rearrested in Saudi Arabia for any reason--an astonishingly low recidivism rate of less than 9 percent among those released.

Although the Saudi efforts to reintegrate these prisoners into society are certainly commendable, the only reasonable explanation for such a low recidivism rate is that the detainees were never guilty of terrorist acts in the first place. For years, Pentagon officials have claimed that the recidivism rate for prisoners released from Guantánamo is about 7 percent. Information released in May by the Department of Defense further buttresses the Saudi findings of a very low recidivism rate. The department's list of named released detainees who have subsequently engaged in militant or terrorist activities anywhere in the world shows that 12 have done so, a recidivism rate of just 2 percent. In fact, the Pentagon can cite only six instances in which an inmate released from Guantánamo actually took up arms against the United States.

When recidivism rates for criminals typically run in the more than 60 percent range, and when at Guantánamo you have a rate in only the single digits, you don't have much of a criminal (or in this case terrorist) population to begin with. We are hardly saying there are no terrorists at Guantánamo. Khalid Sheikh Mohammed, the operational commander of the 9/11 attacks, and others who were transferred there from secret overseas Central Intelligence Agency prisons in 2006 are certainly members of al Qaeda's hard core.

What we are saying is that new statistics from the Saudi Ministry of Interior, corroborated by the Pentagon's own findings, show that the overwhelming majority of individuals detained at Guantánamo not only were not terrorists, but were likely innocent of any crime. Given the sad history of detaining men without charges or proof, proven instances of harsh confinement, and now, persuasive evidence to indicate that most detainees were innocent of any terrorist activity, it should be among the highest priorities of the next U.S. president to close Guantánamo promptly.

Guantánamo has been a powerful recruitment tool for extremists and a stain on the reputation of the United States. Now we can say, with little doubt, that it did not even serve to remove terrorists or insurgents from the battlefield.