TORONTO -- First Nations documentary maker Alanis Obomsawin says she's equally passionate about all of her films, which number in the dozens, but her latest has her particularly emotional.

That's because "Trick or Treaty?" -- which will make its world premiere at the Toronto International Film Festival on Friday -- features the late Dr. Stan Louttit, Grand Chief of the Mushkegowuk Tribal Council, who died in Moose Factory, Ont., in June.

The 82-year-old says Louttit was the reason she made the film, which examines modern-day discussions surrounding a controversial 1905 land rights agreement known as the James Bay Treaty or Treaty No. 9, and seeing him in it now is "just heartbreaking."

"I just feel sick over the fact that he's not going to be there when the film comes out," Obomsawin said at a recent film festival press conference, in which she teared up at the podium as she discussed the film.

"He had cancer, but I certainly didn't think it would happen so fast. It's a loss to all his people and to all of us."

Obomsawin said she embarked on "Trick or Treaty?" after Louttit told her about plans for a re-enactment of the 1905 signing of Treaty No. 9 in northern Ontario.

The veteran documentarian, who has been making films on indigenous history for four decades, travelled to Moose Factory to shoot the event. That footage is in "Tricky or Treaty?" along with scenes from various events surrounding the issue, including the Idle No More movement and Attawapiskat Chief Theresa Spence's hunger strike.

Interviewees in the National Film Board of Canada doc include Louttit, who was a key figure in Treaty 9 education initiatives, as well as various First Nations leaders and experts.

Louttit says in the doc that when the treaty was signed in 1905, First Nations people thought it was an agreement of peace, prosperity and friendship.

And Nipissing University professor John Long, author of "Treaty No. 9: Making the Agreement to Share the Land in Far Northern Ontario in 1905," notes the treaty was not just a written agreement -- it was also an oral one.

"This (film) is so badly needed, I think, because people are very ignorant in terms of knowing what a treaty is -- especially Canadians in general," said Obomsawin.

"If you say 'treaty,' 'Oh, it's an old thing, it's not important.' Well, they're going to find out differently because all the treaties that were made have had terrible consequences to our people and to the country, and people should know that.

"These things should be taught in school."

Obomsawin was at the fest just last year with "Hi-Ho Mistahey," about a campaign to provide quality education for First Nations communities. The year before she released "The People of the Kattawapiskak River," about the conditions inside the Attawapiskat First Nation.

In all, she's produced more than 30 documentaries on aboriginal rights issues for the NFB -- a prolific stream of work that earned her a humanitarian award for "exceptional contributions to community and public service" at the Canadian Screen Awards in March.

She said she's always working on several films at a time (right now she has two other docs on the go), noting they "all marry well together."

And she feels aboriginal filmmaking has gained a lot of traction in recent years.

"I've seen a lot of changes in the last 40 years because for the longest time Hollywood was making films and we became invisible, and Hollywood had its own tribe and it was very different and the people were misinformed," said Obomsawin.

"So now, especially in the last 15 years, 10 years, it's amazing. There's a lot of young people making films, making video, and we have APTN, our own channel. It's just unbelievable.

"It's a very exciting time."

The Toronto film fest runs Sept. 4 to 14.