They intervene here because the Hornets is owned by the NBA ( The 29 owners are the ones paying the bills and the Salary ) so they need the majority to approve the trade wich they didn"t so the trade was called off. Different situation from the Miami Trade.
Chris Paul will not report to the Hornets training Camp and D12 asked to be traded to the Nets.

At the Lakers locker room right now, how akward would it be.
The other 29 owners do not own the Hornets. The NBA owns the Hornets.
The General Manager of the Hornets was told specifically by David Stern and the NBA offices that they had carte blanche to make trades for the benefit of the team, without interference of the NBA. That same general manager that had to be talked out of resigning his post last night when this trade was cancelled by David Stern. David Stern was forced to call off the trade because other owners cried about it when they were ratifying the new collective bargaining agreement. The owners did not veto the trade because the other owners CANNOT veto a trade. It doesn't work that way.
It is the same situation as when the Texas Rangers a few years ago had to file for bankruptcy and was temporarily taken over by MLB. The other owners had absolutely no input in any dealings that the Rangers had made. None.
What David Stern did last night is going to have ramifications unlike anything that we have ever seen before. Let's look at this logically.
The Lakers were not the ones hurt the most by this, nor were the Rockets. The team that was hurt by this the most were the New Orleans Hornets. They are now hamstrung with a player who simply does not want to be there. Plain and simple. There was only one team that Chris Paul publicy stated that he wasinterested in going to, and that was the New York KNicks. In regards to the Lakers, it was reported that he was amiable to signing a long term contract extenstion with them, but his preferred destination was New York.
Now, you can forget about that happening as well. And you can forget about Boston, or any other Big Market team getting Chris Paul, because if the main gripe of the other owners was the fact that Chris Paul was going to go to a big market team, then there is no way that David Stern can allow him to go to Boston or New York, without looking like the biggest hypocrite in the NBA.
The package that was going to be received by New Orleans, and this is based off of the opinions of Chris Broussard, Stephen A Smith, Marc STein, Ric Bucher, Adrian Wojarnarski, and others in the US Media have all said that this was a very good collection of players and picks, especially considering the contract situation.
Now, there is no way that New Orleans is going to be able to get anything remotely close to a deal like that, for the simple fact that teams are not going to be willing to part with prime players and/or picks for a player who will amoutn to being a one year rental, which is what I have been stating time and again for the past 2 days in regards to this.
David Stern just screwed over the one team that is owned by the NBA. THe one team that is under his watch in making sure that the best interests of the team are looked after. Now, there is no possible way for New Orleans to get even remotely close to fair value for him. You can absolutely forget that happening.
And now, how Ironic, that moments after this trade was cancelled, all of a sudden Dwight Howard has announced that he wants to be traded for the Nets. SO let me get this straight. David Stern has just blocked a deal to the Lakers because "He doesn't want players to dictate where they want to play next", but somehow Dwight Howard is going to be traded to New Jersey? Talk about the worst possible timing for this announcement to take place.
A commissioner has never forced a cancellation of a trade before. Fine, the Lakers don't get Chris Pual. As a fan of the team, I can live with that. But what I cannot accept is a commissioner simply stepping in, and blocking a trade, because of the other owners complaining about it. Where were these owners for the Pau Gasol deal in 2008? Where were they last year when Miami was basically giving everyone away for the purpose of fitting Lebron/Wade/Bosh under the salary cap last year?
and FYI. Chris Paul is contemplating a lawsuit against the NBA because of David Stern blocking the trade.
And for those who are screaming about big market/ small market teams and the lack of competitive balance. Oh the irony in those statements, considering that we are talking about this on a forum of a team, who up until 5 years ago, was the most dominant team in Italy and a European power. You can't have ti both ways