Double dissolutions, trigger legislation, Senate quotas, and something called the ABCC. Yes, national treasure Antony Green is back on TV, and everyone in politics has something to say.

Skip Twitter Tweet FireFox NVDA users - To access the following content, press 'M' to enter the iFrame. .@TurnbullMalcolm I admire your methodology, Prime Minister. If you don't like how the table is set, turn over the table. — House of Cards (@HouseofCards) March 21, 2016

So what's going on in Canberra?

This morning Prime Minister Malcolm Turnbull dropped a bombshell - he said if the Senate doesn’t pass legislation, he will call a double dissolution. Apparently he made the decision last night and told his Cabinet via a phone hook-up only minutes before the public announcement.

Skip Twitter Tweet FireFox NVDA users - To access the following content, press 'M' to enter the iFrame. PM has called for both houses to debate ABCC bill on April 18. If it fails to pass, there'll be a double dissolution, w. election on July 2 — triplejHack (@triplejHack) March 20, 2016

But that's just the short story. Here's what you need to know.

If there’s a double dissolution, when will the election be?

The Prime Minister says Saturday, July 2. If there’s not a double dissolution, the election would probably be in September. It has to be held on or before January 14 2017.

He’s chosen that date because if the election was in the first half of the year the next election would have to be in 2018. By naming it July he’s given himself until 2019 to have the next election. Basically it means an extra year in power for whichever party wins.

What’s a double dissolution election?

It’s like a normal election but the whole Senate goes to the polls, instead of half. Every Senator is up for election, even the ones who were elected in the 2013.

It means the list of Senators you can vote for will be much longer.

It also means the Senators need half as many votes to get elected. This amount is called the quota. In a normal election it's 14.28 per cent, in a double dissolution it's 7.7 per cent.

So...will there be a double dissolution?

That depends on whether the Senate passes the government’s legislation. If it doesn’t, and the bill is blocked twice, the PM can call a double dissolution.

This blocked legislation is called the trigger.

The last time we had a double dissolution election was in 1987. Bob Hawke was PM and John Howard Opposition Leader. It was triggered by legislation proposing a national identification card for Australian citizens. Hawke won the election but abandoned the legislation.

In this case, there are two potential triggers, and both have to do with industrial relations. The first is to restore a building industry watchdog, called the Australian Building and Construction Commission. The second is to establish a commission that will investigate and monitor “registered organisations” such as unions.

Neither pieces of legislation have been supported by Labor or the Greens.

“This, for the union movement, is absolutely a bottom line issue,” says the ABC’s political editor Chris Uhlmann. “They see this legislation as appalling.”

“So I can't see how they could amend this Bill to make it satisfactory to either the Labor Party or the Greens.”

“It would appear the Prime Minister is going to allow very limited amendments if any amendments at all into Bill. So the Senate will either pass what the government puts to it or he will see them at an election. So he is calling the Senate's bluff.”

Uhlmann says this is a decisive move by the Prime Minister, taken without much or any consultation with Cabinet. It’s a “captain’s call”.

“He has done his homework on this,” Uhlmann says.

What’s the ABCC again?

The ABCC legislation would restore the Australian Building and Construction Commission that was axed by Kevin Rudd’s government in 2007. The Coalition says the ABCC will monitor and promote appropriate standards of conduct throughout the building and construction industry, while the construction unions see it as an attempt to weaken their position.

It was passed by the House of Representatives late last year and then rejected by the Senate. This meant it went back to the House of Reps - they passed it again and then it went back before the Senate. The Coalition needed six of the eight crossbenchers to pass the bill.

It fell short and the bill was referred to a committee.

According to the ABC, there’s one senator definitely supporting the legislation, three against, and four in the ‘maybe’ camp. This is important because if enough crossbench senators choose to pass the legislation, there’ll be no double dissolution.

Skip Instagram Post FireFox NVDA users - To access the following content, press 'M' to enter the iFrame. A video posted by triplejHack (@triplejhack) on Mar 20, 2016 at 6:17pm PDT

Why does Turnbull want an early election?

Uhlmann reckons the PM is trying to get momentum back into the government. He’s been sliding in the polls, and he could slide further. By having an early election he takes advantage of the last of the ‘honeymoon period’ he’s enjoyed since becoming PM late last year.

It also makes him appear more decisive, Uhlmann says. The announcement shifts attention away from the May budget and the tax debate, where Labor has been doing well.

Turnbull says it’s not only about tactics - he wants the industrial relations legislation passed, and the Senate has so far refused.

“The only reason to go to a double dissolution is to resolve a deadlock,” he said this morning. “These are two big industrial laws which will basically clean up union corruption.”

Why didn’t he call it earlier then?

Partly because he wanted to first pass the Senate voting reforms, according to ABC election analyst Antony Green. These are the reforms that limits the flow of preferences between parties and make it harder for a party to be elected with a small proportion of the vote.

For example, in 2013 Motoring Enthusiast Party’s Ricky Muir was elected with less than one percent of the primary vote. “Somebody being elected with a very low vote like Ricky Muir would be highly unlikely under the new system,” Green says.

Because the Coalition does not have control of the Senate, it’s hard to negotiate with the minor party crossbenchers to pass legislation that is oppose by the Greens and Labor.

The double dissolution election could get rid of these minor party cross benchers and make it easier for the Coalition to pass legislation.

But it’s still a gamble. Because the quota is lower (remember it will be halved to 7.7 per cent), it’s also easier for minor parties to be elected.

“The coalition will probably end up with the same number of seats or slightly fewer,” Green says. “The Labor Party might gain some seats. As far as other parties, it's very difficult to determine … The question is how many other parties get elected and what numbers do they have in the crossbench to pass legislation?”

Green says Nick Xenophon could get as many as four senators in South Australia and Lambie and Lazarus also have a good chance of being re-elected.

So what now?

Turnbull says he will bring forward the federal budget by one week to May 3. The House of Representatives had not been scheduled to meet until May 10, (the original date the budget was to be handed down), but now it will meet on April 18 and sit for three weeks.

If the ABCC legislation and the registered organisations bill are rejected by the Senate in this three-week period, Mr Turnbull says he will call a double dissolution.

What does Labor think of all this?

Game on. Bill Shorten says Labor is ready for an early election.