Heirs of a wealthy New York art dealer were left a $65 million sculpture that might just be more trouble than its worth.

Illeana Sonnabend, who died in 2007, left an art collection worth an estimated $1 billion. But one item in particular, Robert Rauschenberg's “Canyon,” is an heir's nightmare, a lawyer's dream and an IRS conundrum. The bequest comes with a $29 million tax bill, but since the piece includes a stuffed eagle, it can't be sold, according to The New York Times.

Lawyers for Sonnabend's children and beneficiaries, Nina Sundell and Antonio Homem, are hoping federal tax collectors change their valuation of the item, since they're stuck with the piece - and the taxes on it. But for now, the IRS isn't budging, and the case may be decided by a jury.

“We are hopeful for it to be resolved before a trial,” tax attorney Ralph Lerner told FoxNews.com.

Federal law makes it a crime to possess, transport, sell or otherwise convey a bald eagle, whether it is alive or, as in this case, stuffed. Sonnabend got an informal waiver from the U.S. Fish and Wildlife Service in 1981 that allowed her to keep the piece, considered a masterwork of 20th century art. (Rauschenberg got a waiver for the artwork by showing that the bird had been killed and stuffed long before the restriction was enacted.)

Sonnabend died in 2007 at age 92. The estate tax, which at the time of Sonnabend's death stood at 50 percent on estates above $1 million, was suspended in 2010 as part of the Bush-era tax cuts, which were renewed and remain in effect until the end of this year.

Placing a value on an item that cannot be sold is no easy feat. The venerable auction house Christie’s placed the value of "Canyon" at zero. The IRS initially put it at $15 million, then jumped the figure to $65 million when Sundell and Homem refused to pay, according to The New York Times.

The IRS, which declined to comment on the matter, is not only asking for $29 million in taxes, but also an $11.7 million “gross valuation misstatement” penalty, according to Forbes.

Sundell and Homem, who could not be reached for comment Tuesday, have paid $471 million in federal and state estate taxes related to the collection and have already sold roughly $600 million worth of art to pay those taxes, Lerner told FoxNews.com.