High Court to rule on Senator disputes

The Court of Disputed Returns will rule on legal challenges to the election of two crossbench senators after the Senate voted on Monday to refer their cases.

The Court of Disputed Returns will rule on legal challenges to the election of two senators. (AAP)

The High Court is set to decide the fate of former Family First senator Bob Day and One Nation senator Rod Culleton, with a decision possibly expected by the time parliament resumes next year.

The Senate on Monday referred Mr Day and Senator Culleton to the High Court, which will sit as the Court of Disputed Returns, a body which convenes solely to decide on electoral disputes.

It last sat after the 2013 federal election in which the Australian Electoral Commission lost 1375 Western Australian Senate ballot papers. It declared the election void and ordered another.

This process can be quite speedy by legal standards - the 2013 election was held in September with the court delivering its decision in February.

Senator Day resigned from the Senate last week, but it still referred his case to the court to examine whether he received an indirect financial benefit from the government as a result of an arrangement involving his Adelaide electorate office.

The office, leased by the government from December 1, 2015, to October 7 this year, was sold to a friend in 2014, but Mr Day's company loaned money to make the purchase and was ultimately liable for the mortgage.

Receiving a financial benefit from the commonwealth disqualifies a person from holding a seat in parliament under the constitution.

Senator Culleton is determined to fight it out after even his own leader Pauline Hanson backed referral of his case to the High Court.

Although initiated on the same day, the two cases are separate.

Senator Culleton's referral stems from a larceny conviction which was later annulled but stood at the time of the July 2 election.

Under the constitution, any person who has been convicted of an offence punishable by a jail sentence of a year or longer is incapable of being chosen as a senator.

Long before the court makes any decision, there's already been extensive speculation about potential replacements.