Australian politicians referred to the High Court over their duel citizenship status will not know their fate until at least mid-October.
Australia's constitution states you cannot be a parliamentarian if you hold dual citizenship, or are entitled to it.
The court held its first hearings on the cases in Brisbane today, and Chief Justice Susan Kiefel ordered the matter be heard in Canberra on 10-12 October.
It is not clear yet how long it could take the Court to decide on the case and announce its decision.
Deputy Prime Minister Barnaby Joyce's political nemesis Tony Windsor has been given permission to join the citizenship challenge in the High Court.
Mr Windsor will argue Mr Joyce has breached the constitution, as he was a dual citizen of New Zealand.
Solicitor-general Stephen Donaghue QC, acting for the Commonwealth, urged the court to hear the matters by mid-September.
Chief Justice Kiefel said she understood the "unusual circumstances" of the challenges, and the "high level of urgency", given it would have an impact on the current make-up of the Parliament.
However, she raised concerns whether the matters could be dealt with that quickly, particularly when deputy Nationals leader Fiona Nash and South Australian senator Nick Xenophon's cases were awaiting formal referral to the court.
Lawyers for Senator Canavan also said the Commonwealth had "underestimated the complexity of their case", given the nature of his Italian citizenship.
Mr Donaghue said the cases of Senator Canavan, Mr Joyce and Ms Waters were different to those of Senator Roberts and Mr Ludlam.
He argued Senator Canavan, Mr Joyce and Ms Waters had no knowledge they could be considered dual citizens under foreign law.
The solicitor-general suggested Senator Roberts and Mr Ludlam knew or should have known.
Lawyers for Senator Roberts criticised the initial timing of the full hearings suggested by the Commonwealth.