Academic and legal work During the 1980s and early 1990s, Haysom was a lawyer for the
human rights law firm Cheadle Thompson & Haysom Attorneys in
Johannesburg, which he had founded with two fellow academics from the University of Witwatersrand, Halton Cheadle and Clive Thompson. His caseload included negotiating in disputes between
Cyril Ramaphosa, then a mineworkers' leader, and the
white-owned mining companies. In that role he helped to draft a new
constitution for South Africa that enshrined equal rights for Black people, minorities and white people. In 2012, Haysom was appointed Deputy Special Representative of the Secretary-General for the
United Nations Assistance Mission in Afghanistan and in 2014 he was promoted to Special Representative of the mission. Assessing the limits of his work for the United Nations in Iraq and Afghanistan led him to "increasingly appreciate what Mandela brought to the table – which was somebody who was bigger than the divisions in society: the absence of a unifying figure in either Iraq or Afghanistan is noticeable". Two years later, in 2018, Ban's successor as Secretary-General,
António Guterres, appointed him as his Special Representative for
Somalia and Head of the
United Nations Assistance Mission in Somalia. He was expelled from the country on 1 January 2019, after only four months in the role, by the
Somali government of
Mohamed Abdullahi Mohamed, which claimed that he had threatened the sovereignty of the country after questioning the legal basis of the arrest of
Mukhtar Robow. The
United Nations Security Council expressed regret at Somalia's decision to expel a United Nations envoy who questioned the arrest of an extremist group defector-turned-political candidate. Haysom then served as the Secretary-General's Special Adviser on
Sudan from 2019 to 2020 In 2021, Guterres announced Haysom's appointment as his Special Representative and Head of the United Nations Mission in
South Sudan. ==Personal life and death==