The first two Labor members caught in the citizenship fiasco may have to wait until March to find out if they can remain in parliament.
Victorian MP David Feeney and ACT senator Katy Gallagher were referred to the High Court last month after it was revealed they may not have correctly renounced their UK citizenship.
Mr Feeney has been unable to provide documents confirming he had renounced any foreign citizenship in 2007, and Senator Gallagher argues she took all steps within her powers to renounce her UK ties before nominating to stand.
The High Court heard in Brisbane on Friday that evidence and experts required for both politicians' cases were still being sought, meaning a full hearing into the matters may not be held until March.
Mr Feeney's lawyer Thomas O'Brien said the Australian Labor Party legal unit gave him accurate steps in 2007 to renounce his UK citizenship and possible Irish citizenship.
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Mr O'Brien said they were still searching for the relevant documents and whether they were received by the Home Office.
A by-election in Mr Feeney's Melbourne marginal seat of Batman could be challenging for Labor, with the Greens already preselecting a candidate in anticipation.
Solicitor-General Stephen Donaghue QC said experts in Senator Gallagher's case disagreed over the "narrow but important" issue as to exactly what date she effectively renounced her citizenship.
The court heard Senator Gallagher took steps to renounce on April 20, 2016 before she nominated to stand in May 2016.
If Senator Gallagher is disqualified, a special count would likely return her running mate on the ACT Labor Senate ticket, union boss David Smith.
The court adjourned to a date to be fixed.
