Papua New Guinea's Supreme Court has ruled the reappointment of the country's governor-general was unconstitutional and invalid.
Controversy surrounded the June installation of Sir Paulias Matane, who critics said was appointed by the government despite numerous breaches of parliamentary process.
On Friday, the full bench of the Supreme Court unanimously ruled that the appointment was unconstitutional because Sir Paulias was not selected after a secret ballot in parliament.
The court found Speaker, Jeffrey Nape, acted unlawfully by presiding over parliament at a time he was acting governor-general.
It also said soon as practical a meeting of parliament should be called to nominate the next governor-general, within 40 days of this order.
The latest ruling comes in a week of political chaos in which cabinet was suddenly reshuffled, Sam Abal was appointed deputy prime minister and Sir Michael Somare faced allegations of misconduct in court.
The prime minister told a media conference on Thursday his lawyers were challenging the Ombudsman Commission's report into alleged improprieties regarding his listing of financial statements.