The dual citizenship scandal engulfing federal politics will come to a head today, when the cases against Deputy Prime Minister Barnaby Joyce and six other MPs go before the High Court in Canberra.

Under constitutional rules, Australian politicians cannot be dual citizens.

The Turnbull government is confident its three MPs who were dual citizens at the time of the 2016 election – Joyce, Nationals deputy leader Fiona Nash and Nationals senator Matthew Canavan – will survive the full bench of the court, sitting as the Court of Disputed Returns.

Attorney-General George Brandis argues the Nationals trio and independent senator Nick Xenophon and former Greens senator Larissa Waters should not be disqualified because they did not voluntarily acquire or retain their dual citizenship.

The hearing will last three days. A ruling could be made as early as Thursday, but the court may decide that longer deliberations are necessary.

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