Air Commodore Bill Boothby (Retd) served for 30 years in the Royal Air Force Legal Branch, retiring as Deputy Director of Legal Services in July 2011. In 2009 he took a Doctorate at the Europa Universität Viadrina, Frankfurt (Oder) in Germany and published ‘Weapons and the Law of Armed Conflict’ through OUP in the same year. His second book, ‘The Law of Targeting’, appeared with the same publisher in 2012. He has been a member Groups of Experts that addressed Direct Participation in Hostilities, that produced the HPCR Manual of the Law of Air and Missile Warfare and that produced the Tallinn Manual on the Law of Cyber Warfare. His third book, addressing Conflict Law, was published in 2014; the second edition of Weapons and the Law of Armed Conflict was published in March 2016. He teaches at the Australian National University, at the University of Western Australia, at the University of Southern Denmark and at the Geneva Centre for Security Policy. He lectures and speaks widely on international law issues.