I do a lot of anti-trust work. I would be surprised if anything anti-trust resulted from this. Courts and federal regulators are both giving a lot of leeway on those rules right now. I know this is a slightly different situation, but I'm hard-pressed to see how a good claim can be made under the Sherman or Clayton Acts.
I have no legal background whatsoever. But I do have a business background. Wouldn't forcing someone to divest an asset that could be worth upwards of $1 billion -- and subjecting them to the tax liability- due to something they simply said - be in violation of those acts?
I'm also not a lawyer, but an economist who works in the anti-trust sector (which is pretty vibrant these days -- I've worked on about a half-dozen mergers in the last year.) I don't know much about law in general, but I'm familiar with the anti-trust laws, because you have to be (the economists at my job get sent to legal seminars just about the Sherman and Clayton Acts). So I'm a relative expert when it comes to this.
Essentially, if the Sterlings want to claim it is unlawful, on anti-trust grounds, and therefore that these laws should prevent the NBA from forcing the sale of the Clippers, they will need to convince a judge (or, frankly, many judges, since there would certainly be an appeal if they convinced judge #1) that the NBA has a monopoly. When we're evaluating whether or not something is a monopoly, we need to consider what its "product market" is -- essentially, what is the NBA competing against. I'll list, from narrowest to broadest, some of the product markets you could argue that the NBA is in (each subsequent category includes the prior categories):
1) Professional basketball
2) Professional sports leagues (MLB, NFL, NHL, MLL, etc.)
3) Professional sports entertainment (NASCAR, Boxing, Wrestling, PGA, Pro Tennis, PBA, Professional Rodeos)
4) Sports entertainment (NCAA)
5) Entertainment in general (movies, tv, music, etc.)
The Sterlings will need to convince a judge that the proper product market is the first. They will argue that the NBA is 30 businesses colluding together and monopolizing, or exhibiting too much control, over the professional basketball market. The NBA will argue that it is a joint venture of professional basketball teams, that collectively helps the teams better compete in the entertainment market. Even if the judge doesn't agree that the NBA should be in the entertainment product market (although I think a strong case could be made that it should), it's highly unlikely that the judge will say that the NBA is not competing with the NFL, NHL, MLB, Nascar, Golf, Tennis, etc. Joint ventures are very much allowed under anti-trust law, as long as they do not excessively harm competition. Indeed, an argument could be made that prices of MLB, NHL, NFL, etc. might rise if the NBA did not exist. In fact, I'd be surprised if a good argument could be made that prices of those leagues would not rise if the NBA didn't exist. That fact is why the product market will at a minimum be pro sports.
If the NBA is a legal joint venture (which it is by anti-trust standards), then the Sterlings will not be able to use Sherman or Clayton to get out of the contracts they've agreed to. Whether or not the NBA is interpreting those contracts correctly is a completely different matter, and will certainly be litigated, and that's something I'm not remotely qualified to opine on. But an anti-trust argument seems incredibly weak to me, and I'd highly doubt, even if they miraculously found one judge who'd buy it, that the Appellate or Supreme Courts would go along with it. It would just be way too strict in terms of defining product markets -- and would be economically disprovable.