A federal tribunal has — for the fourth time — rejected the bulk of the Art Gallery of Nova Scotia's enormous Annie Leibovitz collection, raising questions about whether the prints by the famous American photographer will ever be displayed in Halifax.

The gallery confirmed Wednesday afternoon that the Canadian Cultural Property Export Review Board has refused to certify the collection as of "outstanding significance and national importance."

"We disagree with the decision," a gallery spokesperson said in a statement. "We consider Annie Leibovitz to be one of the most influential photographers of her time and feel the collection is culturally significant — to our province, our country, and internationally."

This is the latest development in a saga involving doubts about the cultural significance of the 2,000 photos — valued by some appraisers at $20 million — and whether their donation to the gallery by the Mintz family of Toronto was intended as a tax dodge that would profit the family.

Earlier this month, gallery CEO Nancy Noble said it was attempting one last time to have the work certified. She hoped that doing so would "bridge" the distance that's emerged between the gallery and Leibovitz over the Canadian tribunal's repeated refusal to view her work as of outstanding significance to the country.

The gallery has been circumspect about what might happen if the review board again turned down the bulk of the collection.

While the gallery owns the photographs, it has suggested Leibovitz retains copyright and can dictate if and when they are exhibited.

Final decision 'can only be made' by Leibovitz

"Our priority is still to share the work of this iconic and celebrated artist — in our gallery and across the country," the gallery said Wednesday.

"We will talk to the artist to determine the best path forward. At this point the final decision to show the work can only be made by the artist."

Leibovitz has not commented publicly on the decision. The gallery said Noble was out of the country and would not be doing interviews.

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Leibovitz at an exhibit of her work in 2006 at the Brooklyn Museum of Art. (Timothy A. Clary/AFP/Getty Images)

A CBC News investigation revealed earlier this month that the deal struck in 2013 for the Mintz family to buy the collection from Leibovitz would see the photographer paid $4.75 million, but that half the money was contingent on its certification.

The cultural review board's refusal to certify the bulk of the collection means Leibovitz is still out some $2.3 million.

The Canadian Cultural Property Export Review Board is mandated, in part, to determine whether art or other cultural artifacts donated to a designated museum or gallery are of "outstanding significance and national importance" for income tax purposes.

Such a designation can mean generous tax credits for the donor, based on the fair-market valuation of the work.

Repeated rejections

Red flags, however, were raised early on in the case of the Leibovitz collection and it was described by the Canada Revenue Agency as a potential tax shelter for the Mintz family.

The family purchased the prints in 2013 and donated them two days later to the Art Gallery of Nova Scotia. The valuation initially submitted to the cultural review board, however, was $20 million — more than four times higher than the purchase price.

Had that valuation been approved, it would have meant a tax credit for the Mintz family worth millions of dollars more than what they paid for the work.

The Art Gallery of Nova Scotia applied to have the collection certified three times in 2013 and 2014. The review board would only do so for 762 of the prints, which it valued at $1.6 million.

It has repeatedly rejected the remaining 1,300 photographs.

Harley Mintz, a partner at accounting giant Deloitte and the family's point person in the deal to buy and donate the collection, has said it is "simply unfair" to call the donation a "tax grab."

In 2014, the federal government closed a loophole in the Income Tax Act that allowed for valuations far exceeding a recent purchase price, eliminating the prospect that a tax credit could eclipse what the donor paid for the work.