Could native title be the last big hurdle for the Adani mine?

On Tuesday we heard the news that Adani had given the financial go-ahead for its huge mining project in Queensland's Galillee Basin. Representatives from the Indian mining giant and the Queensland Premier, Annastacia Palaszczuk, signed on the dotted line, saying today marked the official start of the controversial project.

It's been a bumpy ride for the $16.5bn project. It's faced legal and administrative challenges from environmentalists, and banks have pulled out of financing the project altogether.

So does the announcement mean the project has the green light to go ahead?

Not quite. The project still faces one significant hurdle, and that is the challenge posed by native title.

Step back a minute - what is native title?

Native title is the legal recognition of Aboriginal and Torres Strait Islanders' ongoing relationship to the land.

If Indigenous groups can prove that land and waterways have been and are still used in traditions and customs, then they have a basis to claim native title over that region.

Indigenous peoples' land rights weren't recognised by Australian law until 1992, when Eddie Mabo successfully challenged Terra Nullius in the High Court. The case overturned the basis of white settlement in Australia - that the land didn't belong to anybody and was fair game, or "Terra Nullius" - and paved the way for native title.

But proving native title can take a really long time, and even if it's granted, it doesn't give traditional owners exclusive rights to that land. It only gives them a say in how that land is used, and in many circumstances other types of land leases and titles overwrite native title entirely.

How does this impact Adani?

The Wangan and Jagalingou people have had rights to the Galilee Basin region in central Queensland since having their native title claim recognised in 2004.

In October 2014, the Adani mining company applied for mining licences in the region. Because native title existed there already, the National Native Title Tribunal had to determine if those mining licences could be granted.

In April 2015, the Tribunal gave Adani the go ahead for two mining licences, if the Queensland Government approved. That's despite one of the traditional owners, Adrian Burragubba, being opposed to the land being used for mining.

Adrian vowed to fight it.

"If the Carmichael mine were to proceed it would tear the heart out of the land," he said in a website dedicated to fighting the mine.

But in August 2016, his legal challenge against the mine was dismissed.

He got a breakthrough in February of this year, when the Federal Court ruled on a separate case in Western Australia, known as the McGlade decision.

It found that a land use agreement was invalid because not all native title claimants had signed it.

Changing native title laws

That ruling had a huge ripple effect around the country, threatening up to 126 past agreements. Adrian used it as a basis to appeal against the Adani mining licences.

The Government introduced legislation that would change the Native Title Act so that the $16bn Adani project wouldn't be jeopardised.

In April, the Attorney General George Brandis tried to rush through debate on the bill, but he was defeated in the Senate. That meant the Government has to wait until the Senate sits again (it's due to sit next week) before the bill can be debated.

Adani wasn't happy. During a visit to India in April, Prime Minister Malcolm Turnbull promised head of the company, Gautum Adani, that he'd resolve the question mark over native title.

"It is a decision that can't be allowed in practical terms to let stand, and there is very strong support for rectifying it," he told reporters.

Opposition Leader Bill Shorten promised Mr Adani that Labor would support the native title changes in Parliament. If Labor sticks to that promise, legislation will sail through easily.

But it's not that clear cut, because Labor itself is divided over the Adani mine.

At a federal level, at least three backbenchers (that is a person who doesn't hold responsibility for a portfolio like, say, defence or finance) have spoken out against the project.

And in Queensland, where Labor is in power, the left faction of the party is strongly against it, forcing Premier Annastacia Palaszczuk to walk a fine line between supporting the mine and listening to members of her cabinet.

In the end she agreed that no taxpayer money would go to the mine, leaving a $900m federal government loan to the state to build a railway for the project in question.