Tonga's Supreme Court has ruled that the 2014 election of Mateni Tapueluelu as a Member of Parliament was unconstitutional and is invalid.
The case was brought by the Acting Attorney General 'Aminiasi Kefu.
Mr Kefu brought the case after he discovered Mr Tapueluelu had possibly breached electoral laws by failing to pay court fines.
Mr Kefu says the constitution stipulates that MPs can only qualify if they have no outstanding fines.
Mr Tapueluelu said he had gone through the government's election registration procedures and was cleared to run.
He argued because the case was being appealed the fines weren't outstanding.
In 2011, Mr Tapuelelu was fined just over US$6,500 after a defamation case brought by a former Minister of Justice Clive Edwards over an article published in the Kele'a newspaper.
For three years, Mr Tapueluelu unsuccessfully took appeals to the Supreme Court and the Court of Appeals.
What happens to his Tongatapu constituency is expected to be addressed when parliament sits in the new year.