A legal battle is brewing between the estate of legendary dealer Ileana Sonnabend and the International Revenue Service over a stuffed bald eagle. Well, sort of — that eagle happens to be part of Robert Rauschenberg’s famous assemblage “Canyon.” The 1959 artwork, which features an eagle with its wings spread wide hanging off the front, was valued at exactly zero dollars in the late dealer’s estate tax return. But the IRS thinks it’s worth quite a bit more: $65 million, to be exact.

The beef really does in fact hinge directly on the eagle, according to Forbes, which reported the juicy tale. According to appraisals from Christie’s and other outlets, the presence of the bird makes the artwork impossible to sell: two federal laws bar possessing or trafficking in bald eagles, dead or alive. (The only reason Sonnabend was able to loan “Canyon” to museums like the Metropolitan Museum of Art, where it is currently on view, is because she got a special permit to do so.) The IRS, however, disagrees with the $0 valuation. It taxed Sonnabend’s estate as if the sculpture were worth $65 million, noting that it frequently applies tax to stolen or illegal goods based on black market value.

Sonnabend’s estate lawyer, Ralph E. Lerner, has now sued the IRS in tax court, and told Forbes he plans to “take it all the way.” He says the estate could never sell such an iconic piece on the black market, and has no plans to try. (It’s worth noting that Sonnabend’s heirs have already paid a great deal of estate tax: They sold off many of her more traditional art holdings in 2007 to pay the initial bill, which amounted to over $400 million.) Still, Lerner said, the chairman of the IRS art panel told him that there could be a market for “Canyon” — “for example, a recluse billionaire in China might want to buy it and hide it.”

Rather than simply seeking to skirt hefty taxes, the estate may have a point that the work is impossible to sell. The eagle issue is somewhat similar to the more common quandry of selling artwork that incorporates ivory. Ivory works made before the Marine Mammal Protection Act of 1972 are legal to buy and sell, while ivory works made after are illegal. Because the Bald and Golden Eagle Protection Act was passed in 1940, it predates "Canyon," which was made in 1959. 

The whole debacle demonstrates just how far we've come since the days when Constantin Brancusi's own bird art — totemic sculptures from his "Bird in Space" series — were taxed as raw material rather than fine art when they were imported into the United States in the 1920s. Someone must have realized that this bird — the bald eagle — was worth far more when attached to a Rauschenberg. Leave it to the IRS to put the “tax” in taxidermy.