Donne had a long legal career in the Pacific. In 1969 he was seconded to the Supreme Court of Samoa, and in 1972 he was appointed Chief Justice. In 1975 he was appointed Chief Justice of the Cook Islands and Niue. In 1978, he presided over the electoral petitions resulting from the 1978 Cook Islands election, which saw the Cook Islands Party of Albert Henry removed from power for electoral fraud.
In 1982 he was appointed as the first Queen's Representative to the Cook Islands. After completing his term, he became Chief Justice of Nauru and Tuvalu.
Donne retired from the bench in 2001 making him one of the longest serving judges in the Southern Hempisphere.