His formal
tertiary education qualifications include undergraduate degrees in history and in law (
BA/
LLB) from
Victoria University of Wellington, a graduate degree in law (
BCL) from the
University of Oxford,
England, where he was a
Rhodes Scholar at
Balliol College, and a doctoral research qualification from the
University of Dar es Salaam,
Tanzania (
PhD) that included an analysis of colonial legal history in
New Zealand, and a
Diploma in
Theology from the University of Oxford (
DipTheol). He is a
barrister and
solicitor of the
High Court of New Zealand and holds a
practising certificate to act as a barrister. He was employed as a legal academic at universities in England, Tanzania, and New Zealand from 1971 to 1991, and during that time he wrote numerous published articles and book chapters on issues related to colonial law,
indigenous law and the
Treaty of Waitangi. From 1992 to 2000, his primary occupation was as a consultant contracted to research on law in history and on Treaty of Waitangi-related legal issues. He has acted in a variety of capacities in contracts with the
Crown Forestry Rental Trust, the
Law Commission, and
Te Puni Kōkiri. He was responsible for the
Māori Land Legislation Manual (and Database) which was published in two volumes by the Crown Forestry Rental Trust in 1994 and 1995. He is the author of ''Te Kooti Tango Whenua': The Native Land Court, 1864–1909'' published by
Huia Publishers in 1999. Williams made front-page-news in 1978 when he walked into an Auckland Police station and asked to be arrested for stealing a pen from his employer. This was a protest against police racism; police had two days earlier had arrested a Pacific Island migrant for stealing a comb from his employer. He has acted as an
arbitrator in respect of
Māori-owned forestry land. He is the honorary legal adviser to
Te Pīhopatanga o Aotearoa (Anglican Church) and a member of the Anglican Church's
General Synod/Te Hinota Whanui. In 2001, he was appointed an
associate professor in law at the University of Auckland, and in 2005 was promoted to full
professor. In 2018, Williams was elected a
Fellow of the Royal Society of New Zealand. == Works ==