Judge Williams was appointed Chief Judge, Maori Land Court in December 1999. Shortly thereafter he was appointed as Deputy Chairperson of the Waitangi Tribunal and has been Acting Chairperson since then.

He completed an LLB at Victoria University in Wellington in 1985. He was a junior lecturer in law at Victoria University in Wellington from 1986-1987, before gaining a Masters degree with first class honours in indigenous rights law at the University of British Columbia in Vancouver in 1988. He returned to New Zealand in 1988 to the firm of Kensington Swan and was made a partner in 1992.

In 1994, he co-founded Walters Williams & Co. He specialised in litigation in areas of resource management and environmental law, Maori issues and Treaty of Waitangi claims, Maori land law, all areas of administrative and public law.

In 1999 he was awarded the Maori Students Millennium Prize as a former student of Victoria University of Wellington. In 2001 he was appointed Fellow of Victoria University of Wellington Law Faculty.