Several First Nations have announced their intention to take the Ontario and Canadian governments to court, in a lawsuit their lead lawyer says could fundamentally change the way resource and land management decisions are made in the Treaty 9 area.

Leaders from 10 First Nations are at Queen's Park in Toronto on Wednesday morning to speak at a news conference. They're filing their notice of action for the lawsuit to Ontario's Superior Court of Justice.

"I think this is going to be the most historic case that has ever been launched in regard to Crown and First Nation relations in this country, and I hope it sets off a chain reaction across the entire land mass," said lawyer Kate Kempton, head representative for the claimants, in an interview with CBC News.

"This is a frontal attack, a direct head-on attack against the worst aspect of colonialism, which is subjugation — the idea that one government can just walk in and take over the government [and] the people who were here."

The plaintiffs claim they never agreed to cede, release, surrender or yield up their jurisdiction to govern and care for the lands, as it says in the written treaty, which was first entered into in 1905.

The First Nations also did not agree the Crown could "take up" lands in Treaty 9 territory without their consent, Kempton said.

"The harm of colonialism lies not so much that other people came and settled, or that the other people took some land and resources, but that they purported to take over, to bestow upon themselves some supreme right to rule it all," says the draft statement of claim.

"The plaintiffs have never consented to the Crown taking exclusive jurisdiction over the land. The Crown's taking and forced imposition of exclusive jurisdiction disabled any ability of the plaintiffs to give or withhold free, prior and informed consent," it adds.

In a news release, Chief June Black of Apitipi Anicinapek Nation said: "We are peoples and nations. We have our laws. We have our lands. We allowed entry onto our lands and use of our lands. But only on the basis that the lands themselves and authority to manage how they are used was to be shared."

Ontario's Indigenous Affairs Minister Greg Rickford could not immediately be reached for comment.

A spokesperson for Canada's minister of Crown-Indigenous relations, Marc Miller, said they could not provide an interview to CBC News at this time.

The treaty should have resulted in a co-management regime where resource and land-use decisions are jointly made by First Nations and Canadian governments on an equal footing, Kempton said.

But that's not what happened.

"Our people agreed to work together, to share in peace and friendship … but were robbed of dignity, livelihoods, our sense of self and ultimately over 100 years of subjugation. We have been attacked culturally and spiritually in attempts to erase our identity through an imposed foreign system and laws designed to remove us from the land," said Eabametoong Chief Solomon Atlookan in a news release.

The implications of the lawsuit are massive, Kempton said, including that possibly every action the Ontario and federal governments took since the early 1900s breached the conditions of the treaty because those actions were done unilaterally without the consent of the First Nations governments.

It could mean some 12 provincial and federal laws — including acts covering mining, fish and wildlife conservation, public lands and fisheries — would be unconstitutional or not applicable in Treaty 9 territory because they were passed solely by Canadian governments, and not in concert with First Nations governments as the treaty requires, according to a draft copy of the statement of claim that was shared with CBC News.

"By extending various legislative schemes to Treaty 9 territory, Canada and Ontario have given themselves the ultimate sole authority to grant and restrict ownership, sale of, use of, access to, exploitation of, development on and harm to the land," it says.

Treaty 9 was first entered into between 1905-1906, when treaty commissioners representing the Dominion of Canada and the province travelled to Cree and Ojibway communities in northern Ontario.

The treaty territory expanded from 1929 to 1930 when two treaty commissioners travelled further into the region and completed signing ceremonies with additional communities.

Kempton said there is ample oral and archival evidence that First Nations were never presented the written terms of the treaty — which were negotiated exclusively between the Ontario and federal governments years earlier — and the oral agreements made between treaty commissioners and the First Nations were not in fact what ended up being written in the treaty.

As a result, the draft statement of claim says, certain clauses in the written treaty text were never agreed to and have no legal basis.

"Treaty 9 is specifically not an agreement that the Crown can take sole jurisdiction … because First Nations never did and never would have agreed to that," said Kempton.

"The evidence is abundantly clear that they agreed the Crown could govern their own people on the use of the land that comprises Treaty 9, but that First Nations would retain their rights and ability to govern as well," the lawyer added.

The lawsuit is seeking $95 billion in damages for Treaty 9 First Nations, as well as injunctions to prevent the provincial and federal governments from regulating or enforcing regulations in the treaty lands without the consent of the plaintiffs.

In practice, Kempton said for example, the injunctions would mean that projects related to the Ring of Fire, a mineral-rich area in Treaty 9 territory that has seen significant proposed mining and infrastructure projects, would not be able to proceed without the consent of affected First Nations.

"The First Nations that are plaintiffs in this case, their intention is to not allow anymore unilateral Crown decision making," Kempton said.

The draft statement of claim has already been shared with representatives for both the Ontario and Canada governments, Kempton said. The plaintiffs will have another 30 days to file their final statement of claim, before the governments will have to respond.