Do former Guantanamo detainees go on to become terrorists?

The future of the US military prison in Guantanamo Bay, Cuba is once again in the spotlight – this time over the thorny issue of recidivism. Every six months, The Director of National Intelligence (DNI) publishes an unclassified Guantanamo recidivism – or 're-engagement' – report, in consultation with the Director of the CIA and Secretary of Defense. The latest one was released on March 7.

But it's already met with fierce criticism.

What is recidivism?

Recidivism is the tendency of a convicted criminal to reoffend. The DNI report on recidivism, however, assumes that detainees held in Guantanamo engaged in terrorist activity before being brought to the camp.

Most of the detainees were not charged or tried in a court of law, so whether or not they actually 'returned to violence' – if they were ever involved in violent acts – is unclear.

Detainees may also have radicalised during their time in Guantanamo given that many were subject to years of physical and mental torture.

The definition of what is confirmed or suspected terrorist activities are vague – and can be arbitrary. They are also not subject to rigour or scrutiny.

"When they actually have to name names and acts that count as recidivism, they can't," law professor Mark Denbeaux, director of the Seton Hall Law School Center for Policy and Research said. "They don't know who did it. They don't know what they did. And they don't know where or why it is that it happened … or anything else."

The Pentagon refrained from naming all of the Guantanamo recidivists, or from defining those activities it considers recidivist.

Why does recidivism matter?

Many oppose the prison as it has held detainees without charge or trial for years.

But supporters say that keeping the remaining detainees – 41 are now imprisoned down from the initial 780 – is crucial for US security, citing rates of recidivism of those who are released from the controversial US prison. Reports that a former Guantanamo detainee Abu Zakariya al Britani conducted a bomb attack on a military base in Iraq has fuelled this debate.

But questions arise over the report. US President Donald Trump tweeted that 122 detainees released under the Obama administration engaged in terrorism. The basis for that, however, stems from a report that says that 113 of those 122 detainees were released under Bush.

What does the report say?

The latest biannual report says puts the rate of recidivism at 29.1 percent. But this number is derived from releases during both the Bush and Obama administrations.

A draft executive order on Guantanamo used the collective rate as means of a proof that the prison should stay open.

However, the report's rate could be deceptive: It includes "suspected terrorist activity," which constitutes 12.4 percent of 29.1. That reduces the confirmed rate of engagement in terrorism by 16.9 percent.

The number of detainees "confirmed" to have engaged in terrorism has dropped to 8 from 9: This means even the rate of detainees who are confirmed to have engaged in terrorist acts is shaky – the government has revised its estimate as to one of the detainees. According to the Constitution Project "DNI considers reengagement "confirmed" if it is more likely than not – i.e., there is a 51 percent chance – that a former detainee is directly involved in terrorism." The Pentagon did not name all of the detainees it counts as recidivists.

The overwhelming majority of 'recidivists' were released under Bush: The administration transferred 500 detainees in bulk transfers, without a strict screening or evaluation process. 113 of the 121 recidivists were released when Bush was in office.

The rate of recidivism dropped to 4.4 percent after Obama took office: According to the report, 8 of the 182 detainees released were "confirmed" to have returned to having committed terrorist acts under Obama.

Upon taking office, Obama reevaluated all the remaining detainees through the Guantanamo Review Task Force that consists of 6 governmental agencies.

Officials from the Office of the Director of National Intelligence, the Joint Chiefs of Staff, and the Departments of Justice, Defense, State, and Homeland Security referred them for transfer, prosecution or continued detention. The non-cleared detainees were reviewed by a Periodic Review Board made up of senior members of the same agencies and offices.