Scott Ludlam, an Australian Greens senator from Western Australia, resigned today, after announcing he had dual citizenship with New Zealand and was therefore in breach of Section 44(i) of the Constitution.

Section 44(i) of the Constitution says that a person is “incapable of being chosen or of sitting as a senator” if they are “under any acknowledgement of allegiance, obedience, or adherence to a foreign power, or is a subject of a citizen or entitled to the rights and privileges of a subject or citizen of a foreign power”.

In a statement, Ludlam said he was born in New Zealand. His family left when he was three years old and settled in Australia when he was nine. “I was naturalised when I was in my mid-teens and assumed that was the end of the New Zealand citizenship.”

Media reports today say that the citizenship question has been previously raised with Ludlam.

Ludlam, 47, was first elected to the Senate in 2007. He took up his seat on July 1, 2008. He was re-elected in 2013 and in the 2014 re-run election. He was re-elected to a six-year term in the 2016 double dissolution election. The Greens polled 10.53% in WA.

Ludlam has been Joint Deputy Leader of the Greens, with Larissa Waters, since May 2015.

It now appears that the Senate will refer the matter to the High Court. Twice this year, the court, sitting as the Court of Disputed Returns, has ordered countbacks following rulings that Rodney Culleton and Bob Day were not entitled to nominate at the election. Assuming this takes place again, the seat will go to the number three candidate on the Greens WA Senate ticket, 22-year-old disability advocate Jordon Steele-John.

Media reports today quote Steele-John as not committing himself to taking the seat. Were he to resign, a casual vacancy would be created and the Greens would nominate a replacement. It would be possible for Ludlam to be appointed in these circumstances, provided he rectifies the citizenship issue. However, Ludlam’s statement and press conference suggested he has chosen to move on to other things.

The practical political implication of today’s resignation by Ludlam is that the Greens will be without one of their number for some months in the Senate. This will not make a significant difference but until the vacancy is filled the Turnbull government will only need eight of the eleven crossbench votes to secure passage of legislation opposed by the ALP and Greens. It currently needs nine extra votes. A pairing arrangement to cover the absence could also be put in place.

Ludlam is the third senator to fall victim to Section 44 since the 2016 election, an unprecedented situation.

• Watch Ludlam’s media conference in Perth (15m)
  
• Listen to the media conference (15m)
  

Statement from Senator Scott Ludlam. Click to enlarge