ACT senator to be represented by former solicitor general Justin Gleeson in hearing that could lead to a rash of byelections in marginal Labor seats

Labor has called in the big legal guns in its attempt to save Katy Gallagher’s place in the Senate.

The Australian Capital Territory senator, who referred herself to the high court over dual citizenship concerns in the last sitting week of parliament, will be represented by the former solicitor general Justin Gleeson.

Gleeson came to public notice after a spectacular falling out with George Brandis, when the former attorney general attempted to stop ministers seeking legal advice from Gleeson without his approval.

Gleeson, representing Barnaby Joyce’s political rival Tony Windsor in the October high court case, was largely seen as delivering the argument that scuttled the government’s hopes its interpretation of section 44 would be the one the court upheld. He presented a black-letter view of section 44’s meaning in relation to dual citizenship, which the court ultimately upheld.

The judgment resulted in Coalition MPs Joyce, and later John Alexander, facing byelections (which they won), and the resignation of Coalition senators Fiona Nash and Stephen Parry.

Dual citizenship and the 'reasonable steps' test for Australian MPs – explainer Read more

Labor is hoping Gleeson, working with Maurice Blackburn and James Mack, who is also serving as a junior barrister in the section 44 case against the National party MP David Gillespie, will be able to replicate his success, this time to keep a Labor member in the Senate.

Gallagher stepped down from her additional parliamentary duties this month after the citizenship audit Malcolm Turnbull ordered in the wake of the high court ruling showed she was still a dual citizen at the time of her nomination for the 2016 election.

She maintains she took all reasonable steps to renounce her British citizenship by descent from her father but a four-month delay in processing her form by the UK authorities meant she did not receive confirmation until after the nomination date.

The outcome of Gallagher’s case, which will have its first directions hearing on 19 January in Brisbane, will have ramifications for fellow her Labor colleagues Justine Keay, Josh Wilson and Susan Lamb. A negative finding for Gallagher could lead to a rash of byelections in marginal Labor seats early next year.

The Batman MP, David Feeney, was also referred to the high court after admitting as part of the citizenship audit he could not locate the documents to prove he renounced his British citizenship in 2007.

Guardian Australia understands Feeney will be represented by Noel Hutley SC in his case.

Labor MPs don't see Katy Gallagher as citizenship test case, Dreyfus says Read more

Labor and the Coalition called an uneasy truce over citizenship in the final sitting week of parliament, to ensure the marriage equality legislation could be passed, after the government threatened to use its numbers to refer all Labor members it believed had eligibility doubts.

In return, Labor, working with the crossbench, attempted to refer Coalition members it said had not provided enough detail or documents to be sure of their eligibility, as well as its own in-doubt members. That attempt, taken while Alexander was absent from the house because of his byelection, fell short by one vote in the lower house.

Both major parties are now looking to the high court to clarify its stance on “reasonable steps” in the Gallagher case.

In the meantime, a bipartisan parliamentary committee is examining ways to prevent any further fallout from the section 44 citizenship fiasco, including whether a referendum is needed to change the constitution.

The committee chair, Linda Reynolds, has told the Australian a referendum would be the “cleanest way” to ensure there was no further fallout.