‘The President is authorised to use all necessary and appropriate force against those nations, organisations, or persons he determines planned, authorised, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harboured such organisations or persons, in order to prevent any future act of international terrorism against the United States by such nations, organisations or persons.’

Written in haste and passed by the US Congress in the days after 11 September 2001, the ambiguously worded Authorisation for the Use of Military Force (AUMF) greatly expanded the war powers of the executive branch, granting US presidents the choice to bomb, raid, detain and monitor nation states and organisations around the world as they see fit. Centred around an interview with Representative Barbara Lee, the sole member of congress to vote against the AUMF, War Authority examines how the authorisation’s vague language – invoked at least 18 times by the former president George W Bush, and at least 19 times by President Barack Obama – has shaped modern US foreign policy and affected people around the world.