1) About 600 people were secretly picked up by US forces from all over the world, and put in a prison in Guantanamo Bay, an area near Cuba controlled by American Navy
2) Families of these prisoners, media or even UN representatives were not allowed to meet them. The US army arrested them, interrogated them, and decided whether to keep them there or not.
3) Amnesty International, an international Human Rights organisation collected information on the condition of the prisoners in Guantanamo Bay and reported that the prisoners were being tortured in ways that violated the US laws.
4) They were being denied the treatment that even prisoners of war must get as per international treaties. Many prisoners had tried protesting against these conditions by going on a hunger strike.
5) Prisoners were not released even after they were officially declared not guilty.
6) An independent inquiry by the UN supported these findings.