Confused by the Bob Day saga? We can't blame you. The issues engulfing the Family First senator from South Australia are complex and require an understanding of voting laws, Senate procedures and the federal constitution.
There's also a chance it could change the makeup of the whole Senate, make it even harder for Malcolm Turnbull to pass legislation, and there's even an outside chance the drama could deliver another senator to One Nation, giving them five across four states.
So it's important to know what's going on.
Who is Bob Day?
Bob Day is a senator for South Australia, for the conservative Family First party. Outside politics, he owned a construction business called Home Australia. He was elected to parliament at the 2013 election, and won re-election at the July poll. However, just weeks after taking his spot in the new Senate, Day sensationally announced his resignation from the parliament after his business went into administration after being dogged by claims of not paying contractors and half-finished homes. Soon after, however, Day said he would be staying on in the Senate for the foreseeable future until Family First could organise a replacement for him; under Senate rules, if a senator resigns in the way that Day initially did, their party can offer up a substitute senator to take their place.
The saga continued with a cloud over Day's head, with pressure on the government not to accept his vote on legislation like the Australian Building and Construction Commission. On Monday, Day finally said he would immediately leave the Senate.
That's where things got interesting.
Just hours after Day's statement, it emerged that the President of the Senate had told senators he wasn't sure if he actually could accept the resignation; there were questions over whether Day was validly elected at all.
So what's going on?
It comes down to section 44 of the constitution, which outlines "disqualification" for election to parliament. A statement from attorney-general George Brandis said the Day matter was "regarding a potential indirect pecuniary interest in a contract with the Commonwealth," which under part (v) of s44, would disqualify Day from being elected at all.
There are claims that Day has a financial interest in the building where his Adelaide parliamentary office is located, meaning the government has been renting office space for Day from a company Day is involved with. This would come up against part (v), which says someone is disqualified from parliament if they have "any direct or indirect pecuniary interest in any agreement with the Public Service of the Commonwealth".
"This raises the question as to whether Mr Day was validly elected to the Senate at this year's federal election. If he was not, Mr Day's resignation would not create a casual vacancy because he was never validly elected in the first place," said Labor Senate leader, Penny Wong.
So what now?
Brandis said that "the Government intends to initiate a Senate referral of the matter to the High Court pursuant to s376 of the Commonwealth Electoral Act". This means they'll ask the highest court in the land what to do next, in terms of filling the vacancy left by Day's departure; basically, whether Family First should be able to put up a replacement, or whether we need to do a recount of election votes to find out who was the next most popular senator to take Day's place.
Depending on the judgment, ABC election guru Antony Green says we'll either get the number two Family First candidate Lucy Gichuhi, or another Labor or One Nation senator.
If the High Court says Day was validly elected, Family First should be allowed to put up their own replacement. If the court says he was not elected validly, either Gichuhi will be elected, or the Family First ticket may be struck out of the running (for some complicated electoral reasons around how parties appear on the ballot paper and whether Day's below-the-line votes should flow through to Gichuhi) and instead the votes recalculated to find who would have been elected if Family First was struck out from the running.
Green was quick to do the numbers:
In a detailed piece that is worth your time to read, Green outlines how new preference flows would likely see another Labor senator elected in Day's place if a full recount is ordered with Day ruled ineligible. Green says One Nation is probably the less likely of the two, in an already probably unlikely scenario where Day is ruled ineligible, but the party's current senators are already crowing.
What does it mean for the Senate, and the government?
Right now, the government has 30 senators in a 76-seat Senate. You need 39 senators to pass a motion, meaning the government right now needs to wrangle either nine Labor members, all nine Greens, or nine of the 11 diverse crossbenchers to pass something. Day has been called the "most compliant" senator for the government, almost always supporting their legislation.
If Labor snatch another senator, that would give them 27 -- nearly as many as the government -- and mean that the government would need nine of the 10 crossbenchers. If One Nation get the place, that gives Pauline Hanson's team five senators across the country, and strengthens their bargaining position. If the Family First candidate keeps their spot, whether that is Guchihu or another party member, there is no guarantee they will be as "compliant" as their predecessor Day was.
It is just another headache for a government that didn't need any more problems.