Retired major general and Liberal candidate Jim Molan can now take his seat in the Senate after the High Court declared he has been duly elected as a senator for the state of NSW.
"There should be no lingering uncertainty and it is in the public interest that that issue be resolved as soon as possible," Justice Stephen Gageler said on Friday in the High Court in Sydney.
Senator-elect Molan replaces former Nationals senator Fiona Nash, who was disqualified by the court for holding dual citizenship.
Justice Gageler was not asked, nor did he rule on, the question of what place Mr Molan would take in the list of 12 NSW senators which determines whether they have three- or six-year terms.
But Mr Molan's barrister, Arthur Moses SC, told the judge there was no dispute between his client and Senator Concetta Fierravanti-Wells that he was entitled to three years and she the six-year term.
Prime Minister Malcolm Turnbull tweeted his congratulations after the court's declaration stating "your vast military experience, courage and wisdom once again deployed in Australia's service".
Mr Molan said he hoped to use his experience in helping defend Australia and working with other countries to achieve democracy "to make a contribution that will benefit the people of NSW and Australia".
Solicitor-General Stephen Donaghue QC, acting for the federal attorney-general, had asked for the declaration on Friday, noting the Senate was scheduled to sit on February 5.
"The order sought will have a limited statutory effect, namely of allowing Mr Molan to take his seat accordingly," the judge said.
Ms Nash was to have been replaced by Liberal candidate Hollie Hughes, but she was found to be disqualified because of her job with the Administrative Appeals Tribunal.
Mr Molan was the next candidate after Ms Hughes on the coalition's 2016 NSW Senate ticket.
After a special count of ballot papers on November 22, Mr Molan was identified as one of the 12 people elected.
The Australian Electoral Commission had indicated that whereas Ms Nash was placed fifth, Mr Molan would be placed 10th and Senator Fierravanti-Wells, who was previously seventh, was fifth.
Justice Gageler also heard arguments from Geoffrey Kennett SC, who was appointed to assist the court on legal issues related to the case.
He argued the declaration order should not be made on Friday as the question of the length of terms or other questions may need to be determined.
But the judge said if such issues arose they could be addressed through further applications.
Speaking outside court, Senator Fierravanti-Wells said it was up to the Senate to determine the order of senators, but it was clear that she took the fifth place of Ms Nash.
