When Senator Matt Canavan recently stood aside from cabinet over concerns he might be a dual citizen and therefore ineligible to sit in parliament, deputy prime minister Barnaby Joyce stepped up to take on Canavan’s duties.

So it was downright inconvenient that Joyce has revealed to the world that he, too, may be ineligible to sit in parliament. No less than New Zealand’s prime minister – confusingly named Bill English – confirmed that Joyce is a Kiwi.

Luckily for the people of Northern Australia, who would no doubt have felt dangerously unmoored without a minister of their own, the prime minister decreed that Joyce, unlike Canavan, did not have to stand aside from cabinet.

This might seem confusing – why one, and not the other? The crucial difference is that in Joyce’s case the prime minister can see the future: “the Leader of the National Party, the deputy prime minister, is qualified to sit in this House, and the High Court will so hold!”

One feels for Canavan, who must devoutly wish his prime minister had acquired his psychic powers just a little earlier.

The prime minister, meanwhile, must devoutly wish the court does what he has said it will. This is the man who once told the nation that Kevin Rudd would have to resign if he had misled the parliament. Oh well, crash or crash through, I suppose.

I’m being facetious, but prime ministers do overstep when they presume the court will act in a certain way. They overstep because there is a separation of powers in this country and politicians must let the courts get on with their work alone. But they also overstep politically in making predictions that can very quickly turn out to be wrong.

The government insists that it has strong legal advice that Joyce is on safe ground. But remember the Gillard government’s Malaysia solution? This was Julia Gillard after the High Court found the plan did not fall within Australian law:

“Our legal advice was that our ability to do this was in the current law, we were advised that our legal case was strong, we were advised that our legal case was strong in part because the courts have considered similar questions in the past and looking to those precedents we were advised that if those precedents were followed our legal case would be a strong one.”

Or in other words, and I am stating what should be obvious here: legal advice is only ever advice. Prejudge the High Court at your peril.

Joyce, to his credit, has not been that eager to attack the other potential dual citizens of parliament, but did recently say, “everybody should check when they become a member of parliament. That’s section 44 of the Constitution. People know what it’s about. They should check.” Do as I say, not as I do.

Once Joyce had announced his difficulties, the prime minister wrote to Bill Shorten generously offering him the “opportunity” to refer any Labor MPs to the High Court for a decision on citizenship. Turnbull concluded his letter:

“The Australian people must have confidence in our political system and resolving any uncertainty is vital.”

What Turnbull didn’t explain was why it had only just become vital this morning. Why was it not vital early last week, when Fairfax first approached Joyce with questions about his potential New Zealand citizenship? Or late last week, when the New Zealand PM was informed of the case, several days before Australians were? Why was it not vital when the Canavan case arose?

It’s this type of thing that – rightly – provokes cynicism among non-politicians. Perhaps Joyce always intended to reveal the concerns publicly this morning. But it seems equally possible he only did so because he knew he was about to be outed. (No doubt Joyce would say he was waiting for legal advice – see above for the irrelevancy of this argument.) And perhaps Turnbull has been writing that letter in his head for weeks, Herzog-style. But more likely, he only wrote the thing because Joyce is a lower house MP, meaning that a by-election in his seat would put Turnbull’s majority government in peril. Remember all those warnings Turnbull has made in the past about chaotic minority governments. Turnbull desperately needs to sprinkle uncertainty around Labor, too.

Shorten, unsurprisingly, declined Turnbull’s kind offer.

While Turnbull’s actions were cynical, Shorten is also wrong. Doubts hover around several MPs from all over the parliament. It would be to everyone’s benefit to have this sorted. But Shorten wants to leave the discomfiting limelight to Turnbull and Joyce. He, too, is being cynical.

Greens leader Richard Di Natale proposed a few weeks ago that there be two separate inquiries, with independent expert panels assessing the eligibility of senators and MPs. If doubts arose, individuals could be referred to the High Court. Di Natale may be acting out of frustration – his two dual citizen senators resigned rather than taking their cases to the court – but he is correct. His solution would be better than the rolling farce we are now witnessing.

A referendum question should be put to Australians in order to fix this constitutional mess. But right now we’re stuck with the Constitution we’ve got, and our MPs must act within its strictures.

Last week, after One Nation Senator Malcolm Roberts confirmed he had been a British citizen, having previously denied it, David Crowe of the Australian tweeted, “And there you have it. Never trust a politician to rule on their own citizenship. The High Court is the place to decide.”

He’s right, and the actions of Turnbull, Joyce, Shorten, Roberts and all the MPs nursing doubts but waiting to be called out, make the point for him.

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