On April 30^th, 1494, Christopher Columbus sailed into Guantánamo Bay. He was in search of El Dorado. He took one look, decided that it was a wasteland, and left the next day.

More recently, it has been nineteen years since the first detainee arrived in an iconic orange jumpsuit on January 11^th, 2002. Later this month, January 21^st will mark twelve years since President Barack Obama announced – as his first significant act in office – that he would close the notorious prison within the year. Here we are: Guantánamo remains open.

The prison comes with a long history, and it has always been about avoiding the rule of law. If you walk into the UK parliament through St Stephen’s Gate, on your left you will see a statue of the First Earl of Clarendon. Quite why he has not been jettisoned into the nearby River Thames is a mystery as he was not a good man. He was an early proponent of rendition – during the English Civil War, enemies of the government were shipped to island prisons where they could be held without due process. He ultimately fled into exile, and the writ of habeas corpus – by which a prisoner could challenge the legality of his detention – was first codified in 1679, in reaction to Clarendon’s excesses.

Ironically, then, more than 300 years on the US copied Clarendon’s tyranny and then claimed that the writ of habeas corpus had no force in Guantánamo. The Administration of George W. Bush thought they could get away with this since the US naval base had earlier been used to house Haitian refugees: they were interdicted on the high seas and taken to Cuba rather than the US mainland, where their rights under the UN Refugee Convention were radically curtailed. Guantánamo had an unhappy pedigree and was consciously chosen in the wake of 9/11 to hold hundreds of bearded Muslim men because the Bush Administration thought they could be held in a Black Hole beyond the rule of law.

In those early days, Secretary of State Donald Rumsfeld said that the 780 detainees were the “worst of the worst” terrorists in the world, captured on the battlefields of Afghanistan. I remember when he said that, and it motivated me to round up two colleagues and bring the first petition for habeas corpus on behalf of Shafiq Rasul on February 19^th, 2002. When such hatred rears its ugly head, my mother taught me long ago that it is our duty to intervene and stand between the baying crowd and the object of their venom.

That said, I was motivated by the principle – everyone deserves a fair trial – rather than a belief that all my clients would be innocent. I thought that if we were able to get in to see our clients, we would probably have some explaining to do: Shafiq was British, and what had he been up to in Afghanistan? It took us 30 months to reach the US Supreme Court and convince a majority of justices that the men had rights. We might not have prevailed but for the shocking pictures that had just leaked out of Abu Ghraib, which sorely damaged the government’s claim to the moral high ground.

But when I first arrived at the prison base, I learned that my own doubts had been misplaced. I found it very hard to find an honest-to-goodness terrorist. Some (at least two dozen) were children. Most were “nobodies”. The explanation gradually became clear: the US had offered large bounties, ranging up to $20 million, for anyone turned over to the CIA as a terrorist. Pakistan President Pervez Musharraf boasted in his autobiography that at least half of the Guantánamo prison population had been abducted in Pakistan – often hundreds of kilometers from any Afghan battlefield.

Meanwhile, everything about Guantánamo was secret, including who was held there – the list remained classified until 2006. It was mad: what kind of democracy locks up hundreds of people in secret? I learned who everyone was courtesy of one of my favorite clients, Al Jazeera Journalist Sami el Haj. Sami was much liked by everyone, detainee and guard alike, and had provided me with a list of each prisoner, his number, his date of birth, and his nationality. What kind of democracy locks up a journalist? Part of me was sad when we got Sami home, as he was the best ally I have ever had, the only journalist to have free access to all the detainees.

My colleague, Professor Joe Margulies, cogently identified the true role of Guantánamo: it was another front in the ‘War of Terror’, propaganda intended to convince Americans that we were winning the battle against Usama Bin Laden. Joe insisted that if we opened the prison up to public inspection, the US would close it down, embarrassed by what the truth revealed.

And so it has largely proved. Of the 740 detainees who have been released to date, none has been ordered free by a court of law – most are now home because we have got to interview them, and then published what we found in the media. Prior to setting each person free, the US has made an official finding that the prisoner is “no longer” a threat to the US. Almost without exception, the reality is that he never was. He was just some unfortunate soul, bought and paid for like a slave, and rendered halfway around the world based on false evidence. The proven “error rate” thus far is a little over 95 percent, and still climbing. Did the world ever know a system that was so fallible?

Nineteen years on, this leaves just forty people left. One might think these would be the “worst of the worst of the worst” after all this time, with the US intelligence agencies free to sort the extremist wheat from the innocent chaff. That has not proven to be true. There are a handful of notorious figures – Khalid Sheikh Mohammed, who claimed to have been the mastermind of 9/11, is one of five people who facing military trials – and yet the majority of the remaining detainees are still “nobodies”.

I represent seven of them. Ahmed Rabbani is a typical figure. He was kidnapped from his home in Karachi on September 10, 2002. He was sold for a bounty to the US, his Pakistani abductors claiming that he was a terrorist called Hassan Ghul. He insisted that he was a taxi driver. The CIA were not sure what to believe so they took him to the Dark Prison in Kabul and tortured him for 540 days. He continued to insist he was not Hassan Ghul, though when they crossed an unbearable pain threshold he would say whatever they wanted to hear.

Eventually he was rendered to Guantánamo – where I first met him 13 years ago. When he told me his dreadful story, I found him credible. Then in 2014 the details were corroborated in dramatic fashion by the US Senate report on the CIA use of “Enhanced Interrogation Techniques”. Ahmed had been tortured, the Senate committee concluded, “without authorization” – leaving us to wonder whether we should deem it better if the US had officially sanctioned it. The Senators then added one fact even Ahmed had not known: while he was held in the Dark Prison, who should the US capture but Hassan Ghul, who they brought to the same torture chamber in 2004. Astoundingly, he was only held there for two days because he was “cooperative” – presumably, unlike Ahmed, he admitted he was Hassan Ghul. So the US eventually released him back to Pakistan, where he went back to his extremist ways and was killed in a drone strike in 2012.

Meanwhile, Ahmed was sent as a “forever prisoner” to Guantánamo. Now he is “forever” ignored, as the world forgets that Guantánamo continues to hold innocent Muslim men. (Six of the forty have been “cleared” for release by all six major US intelligence agencies, some for a decade, yet the US has not released them.) Ahmed has a son Jawad who will be eighteen this year, who he has never met – as his wife was pregnant when he was dragged away. Imagine how you would feel if you never had the chance to touch your son through his entire childhood?

Thus we find ourselves, in January 2021, with a duty to help President-Elect Joe Biden send Ahmed Rabbani and the others home. Most of the men can return to their families; a few, including Rohingya refugee Mueen al Sattar, cleared for release since 2010, need asylum in a country like Qatar. We cannot sit idly by, for there is continued injustice in Guantánamo Bay. And injustice anywhere is injustice everywhere.

• Clive Stafford Smith is an Anglo-American human rights lawyer, the founder of the London charity Reprieve, who has provided free representation to the Guantánamo detainees since the day the prison was opened in 2002.