Washington began obliging airlines to provide it with travellers’personal data after the 11 September 2001 terrorist attacks. With the 9/11 hijackers using the commercial aviation system to such devastating effect, Congress eagerly endorsed the system. The airlines complied more reluctantly, realising it was forcing them to violate EU data privacy rules. Keen to avoid economically damaging disruptions to air travel, the European Commission and the US Department of Homeland Security (DHS) agreed, in 2004, to put the transfers…