Cases against the eligibility of two senators will go to the highest court in the country as parliament returns for the final sitting fortnight of 2016.
A directions hearing for former Family First senator Bob Day and One Nation senator Rod Culleton before chief Justice Robert French is set down for Monday in Canberra at 11.30am AEDT.
Senator Culleton is being taken to the Court of Disputed Returns by the federal government over his alleged ineligibility to run for parliament in the July election because of a larceny conviction at the time.
Mr Day's eligibility is being challenged on the grounds he received an indirect benefit from the government in relation to his Adelaide electorate office.
Senator Culleton, who will be representing himself, has called for a postponement of the case against him arguing it will be in breach of the law for him to appear on a parliamentary sitting day.
Section 14 of the Parliamentary Privileges Act says a member of parliament shall not be required to attend a court on any day when parliament is sitting.
On Friday he argued the government's action was a waste of taxpayers money over a $7.50 key.
"The government may love burning people's money but I'll save my money for Christmas presents. I told Santa to put (Attorney-General George) Brandis on his naughty list too," the West Australian senator wrote on his Facebook page.
Under the constitution anyone with a conviction which carries a potential jail term of a year or more is not eligible to be in parliament.
Mr Day resigned from the upper house on November 1 to deal with the collapse of his home building empire.
The court will examine whether he had a pecuniary interest with the commonwealth as a result of an arrangement involving the lease on his Adelaide electorate office.
Receiving a financial benefit from the commonwealth disqualifies a person from holding a seat in parliament under the constitution.
The government maintains it never paid any rent for the office.
