You miss that the article says it is a crime to possess or even transport the piece. This is like arguing that if you can't sell it without double parking, it's worth $0 and you don't owe taxes.
Your analogy wasn't very clear. What I'm saying is if they have no way of making money off it what taxes do they owe? If you buy shares in a company that goes bust but you still have the paper should you pay taxes on that if the IRS decides its worth something?
I thought like you until the middle of the article, in the place I quoted. It's not that they have no way of making money off of it - they are only saying that. I would believe it if they got a letter from the wildlife agency saying, oh, no, we are only exempting your possession: we can't extend it to your selling to a museum. But that's clearly not the situation. They obviously have every ability to sell to, e.g. the museum currently displaying it, and it will be approved.
they're trying to use a technicality - that it's "technically" illegal. don't do that. if they were serious they wouldn't even possess it, since that's "illegal" too. read the article carefully to see what I mean.
You're missing two key understandings of the Bald and Golden Eagle Protection Act: First, the Act allows museums and similar institutions to own and transport bald eagles. Second, the article states that the bird was acquired prior to the Act taking effect in 1940. That means that current possession is legal, provided that it doesn't change ownership. For a similar situation, look at zoning laws. A property can be "legal nonconforming" because it was, at one time, in compliance with zoning laws but is not any longer. Why? Because both types of laws carry criminal penalties and it is unconstitutional to retroactively make something a crime. The artist can keep the bird, will it to his heirs (generally, passage to one's heirs doesn't trigger "change in ownership" laws), and do the other trappings of ownership but No One Else Can who isn't able to comply with the law, like a museum. Ergo, his heirs can't sell it except to the museum. The museum isn't willing or able to buy it--the piece is already on loan to them for free--so there is no market and, therefore, no value.
Where do you get the idea that museums wouldn't or couldn't purchase the work, assuming this purchase is OK'd by the government first - which given the history here and the work in question the family can easily count on?
Your comment doesn't make sense in light of the fact that the family was forced to put the work on display, which doesn't sound like they "can do the other trappings of ownership but No One Else Can".
The article says: "Indeed, the only reason Mrs. Sonnabend was able to hold onto 'Canyon', Mr. Lerner said, was due to an informal nod from the United States Fish and Wildlife Service in 1981. {P} Even then, the government revisited the issue in 1998. Rauschenberg himself had to send a notarized statement attesting that the eagle had been killed...before the 1940 law went into effect. Mrs. Sonnabend was then able to retain ownership as long as the work continued to be exhibited at a public museum. The piece is on a long-term loan to the Metropolitan Museum of Art in New York, which Mr. Lerner said insures it, but the policy details are confidential."
This does not sound to me like it matches what you are saying at all. Quite to the contrary, it sounds like this work is quite special and important and for this reason was given these exemptions - this makes it quite likely for a sale to a museum to be approved, and the family has every reason to believe this.
So we must return to why you would say that a museum wouldn't or couldn't buy it (after saying earlier in your comment that museums were allowed to own such works, though the article does not make this blanket statement.)
Your arguments have no basis in the law *as it exists in this reality. The law makes it a felony to sell or possess bald eagle remains. The only reason that family still "has" this art piece is because actual possession of the art piece lies with the museum; the family retains "legal" ownership but cannot ever actually exercise possession without violating the law.
The family does not have a reason to believe that a sale to a museum would be approved since that would be a clear exception to the explicit text of the law. The prior "exception" does not change this because it does not actually conflict with the terms of the law.
You need to either (1) learn the law or (2) stop pretending like you know what you are talking about. Armchair lawyers like you ruin the discussion of legal articles on HN.
I will just say that if it were me in this situation, I would never in a million years go on an art appraiser's word that I 'can't' sell it, without even asking the appropriate agency.