 People often assume that public law, constitutional law, is about very big picture questions. How are laws made? How does devolution work? What is the UK's legal relationship with the European Union? Public law is about those things, but it's also about how that big picture relates to and impacts upon, sometimes in very stark ways, real people. Sometimes those people are marginalised and unpopular, and the question arises whether the majority in society are and should be free to treat such people as they wish, or does, should the law prevent the majority from advancing their own interests at the expense of the weaker and the more vulnerable? Those are the questions that lie at the heart of the Belmarsh prison case, or more formally the case of A and the Home Secretary. And that's what I'm going to talk about here. Our story begins, however, thousands of miles from Belmarsh prison in London. It begins in the northeastern United States. As everyone knows, events in that part of the world on September 11th 2001 and most iconically at the World Trade Centre in New York changed the course of recent history. As well as causing some of the most significant geopolitical events of the last decade, 9-11 gave rise to a climate of fear that's unparalleled in recent times in comfortable, secure Western societies. That was certainly the case in the UK. As a key strategic ally of the US, it was perfectly reasonable to suppose that if Al Qaeda could strike in Washington DC and New York City, then London might be next. Against that background, legislation which became the Anti-Terrorism Crime and Security Act 2001 was rushed at top speed through the UK Parliament in the days and weeks following 9-11. The Act was very long and complicated, covering a sweep of matters from police powers to nuclear and aviation security. But if all the provisions contained in the Act, one set, known as Part 4, was especially striking. So here's how Part 4 worked. The Home Secretary, a member of the government, could issue a certificate against somebody if certain conditions were met. What were those conditions? Well first, she had to reasonably believe that the person's presence in the UK was a risk to national security. Second, she had to reasonably suspect the person of being an international terrorist. And third, the person concerned had to be a foreigner, in other words, not a UK citizen. If someone met those conditions, then a certificate could be issued. And then what? If it was not possible to deport the person, then they could be detained instead. In other words, people who had certificates issued against them, but who couldn't be removed from the country, could instead be imprisoned. And that didn't mean imprisoned after having been convicted of a criminal offence following a fair trial before an independent court of law. It meant imprisoned for an indefinite, open-ended period on the say-so of a government minister. Of course, people, including terrorist suspects and even foreign terrorist suspects, have human rights. And one of the most fundamental human rights is the right to liberty. That right has been recognised in British law for centuries, and it's now enshrined in the European Convention on Human Rights. Article 5 of the Convention says that everyone has the right to liberty, and that a person's liberty can only be restricted in very limited circumstances. For example, when an independent court of law has found someone guilty of a criminal offence and sentenced them to a term of imprisonment. But it's very clearly a breach of the right to liberty to imprison somebody indefinitely without a fair trial, and at the direction not of an independent judge, but of a government minister. So how could this happen? How could the UK make a law so clearly in breach of fundamental human rights? The government, of course, had anticipated all of this, and it had a card of its sleeve. That card was another part of the European Convention, a sort of get-out clause. Article 15 of the Convention says that in very grave circumstances it is lawful to, in effect, suspend some human rights, including the right to liberty. At the same time, however, there are some rights that Article 15 does not allow to be suspended. One such right is the right not to be tortured, which includes the right not to be deported to countries where there is a real risk of torture. That's why the government couldn't deport some foreign terrorist suspects. They came from countries known to practice torture, and the government therefore sought to imprison them in the UK instead. The government's case then was that following 9-11, the security situation was so severe that Article 15 allowed the right to liberty to be suspended. The suspects who were being held in Belmarsh Prison disagreed, and that disagreement was what the court had to resolve in the Belmarsh Prison case.