Andrew Thomas Cayley, (born 1964), is an English Queens Counsel and currently the United Kingdom's Director of Service Prosecutions. He was the International Co-Prosecutor of the Khmer Rouge Tribunal in Cambodia from 27 November 2009 until 16 September 2013. Prior to this he was a Senior Trial Attorney at the International Criminal Tribunal for the former Yugoslavia and the International Criminal Court in The Hague between 2001 and 2007. At the ICC he was responsible for the investigation and prosecution of serious violations of international humanitarian law in the Darfur region of Sudan.
Cayley was educated at Brighton College and then University College London (LL.M 1986) and the College of Law Guildford ( Law Society's Solicitors Final Examination 1988). He was admitted as a Solicitor of the Supreme Court of the Judicature of England and Wales in 1989. In 2007 he was called by the Inner Temple to the Bar of England and Wales. After a period in private practice, as a solicitor, until 1991 with the law firm Thomas Eggar, he served with the Army Legal Services of the British Army first on attachment to the Kings Own Royal Border Regiment in Belize and then as a military prosecutor and command legal adviser in Germany and the United Kingdom. He attended the Professionally Qualified Officers' Course at the Royal Military Academy Sandhurst.
Placed on loan service in 1995, as a military prosecutor, by the Foreign & Commonwealth Office and the Ministry of Defence to the International Criminal Tribunal for the Former Yugoslavia ("ICTY") he investigated and prosecuted the cases of The Prosecutor v. Colonel Ivica Rajic (Stupni Dol), The Prosecutor v. Colonel Tihomil Blaskic, the Prosecutor v. General Radoslav Krstic (Srebrenica)and The Prosecutor v Radoslav Brdanin and General Momir Talic. He retired from the British Army in 1998 and was immediately appointed as prosecuting counsel with the ICTY. In 2001 he was appointed a Senior Trial Attorney of the International Criminal Tribunal for the Former Yugoslavia by Carla Del Ponte, Prosecutor of the ICTY. In that capacity he was responsible for the case against General Ratko Mladic and led the first prosecution of members of the Kosovo Liberation Army.
In February 2005 he was appointed Senior Trial Attorney at the International Criminal Court by the Prosecutor Luis Moreno Ocampo. In 2007 after filing the first case for war crimes and crimes against humanity in Darfur he departed from the ICC and was immediately instructed by Mr. Ivan Cermak to defend him in his case before the International Criminal Tribunal for the former Yugoslavia and by the former President of Liberia Charles Taylor in his defence before the Special Court for Sierra Leone.
Cayley was appointed Queen's Counsel in 2012. He was appointed Companion of the Order of St Michael and St George (CMG) in the 2014 Birthday Honours for services to international criminal law and human rights. Also in 2014 he became a governing Bencher of the Honourable Society of the Inner Temple. He was appointed Fellow of the Royal Society of Arts in 2017. He is a member of Temple Garden Chambers.