How many principles have we scrapped since 9/11? A new Guantánamo film reminds us | Shami Chakrabarti

The Mauritanian tells the true story of Mohamedou Ould Slahi, whose plight has left a stain on ideas of Anglo-American justice

I started work at Liberty, the civil rights advocacy group, the day before the September 11 attacks. I recall the feeling of doom: it is important to remember the devastating loss of life on that day - 3,000 people from all over the world - in an event that is now often subject to denialist conspiracy theories. Soon after, British ministers were contemplating far-reaching security measures" against the background of fear that the same could happen in London. Surveying the entire population was a price worth paying, they said.

Having worked at the Home Office before joining Liberty, I knew the that way Britain treated migrants - who are subject to fewer protections than citizens - might well become the framework for the UK's draconian approach to anyone suspected of terrorism. But I never predicted how long the post-9/11 legacy would linger. And with my Hollywood ideals of Anglo-American constitutional norms, reflected in movies such as A Few Good Men, I never imagined that the use of torture would become a systematic technique of interrogation.