He served as president of the Court of Appeal from 2022 to 2024. Cooper is of Ngāti Māhanga descent, an iwi of Waikato Tainui.

[1][2] He received his tertiary education at the University of Auckland, graduating with Bachelor of Laws (Hons) and Magister Juris (Dist) degrees in 1979.

[5] In 2004, Cooper was appointed a high court judge by the attorney general, Margaret Wilson, and sat in Auckland from August that year.

[9] Cooper was on the executive of the Auckland Division of the Cancer Society of New Zealand.

Cooper was board member for the Museum of Transport and Technology and the Auckland Observatory and Planetarium Trust.