Tonga's chief justice Gordon Ward has resigned to take up a position in Fiji's court of appeal.
Tonga's secretary for justice, Simi Tekiteki, has confirmed the resignation.
Justice Gordon Ward's 10-year contract with the Tongan government was to have been completed in 2008 but he is leaving early, giving three months' notice.
During the past year the relationship between Justice Ward and the Tongan government has been strained after he ruled some Privy Council ordinances illegal and unlawful in the government's efforts to ban the Taimi o Tonga newspaper.
The government ignored some of Justice Ward's rulings and turned some of the illegal ordinances into bills which became law after amendments to the Tongan constitution.
Mr Ward was previously chief justice of the Solomon Islands and before that had worked as Fiji's chief magistrate until the 1987 Rabuka coups.