To hopefully end all confusion on this topic (especially mine) I contacted Mitchell Nathanson, author of The Irrelevance of Major League Baseball's Antitrust Exemption: A Historical Review from 2005 and Legal Professor at Villanova Law School about the A's territorial issue. Here is his response:
I think that if the A’s want to move to San Jose, all they have to do is move there. Nobody is going to stop them. Technically, if the antitrust exemption had any teeth, you’re correct that a ¾ vote could stop them but since the exemption is meaningless, I don’t believe that MLB, or the Giants, would press the issue in a court of law although technically they’d have that right. Right now, the only thing that is keeping the A’s in Oakland is their desire to get along with their fellow teams – they simply don’t want to anger Selig or the Giants’ management. But they really don’t have to do this if they don’t want to. Trust me, if Al Davis owned the A’s, they would have been in San Jose 10 years ago, with or without an antitrust exemption.
As for Congress, that’s a red herring. They don’t need to engage Congress and ask them to remove something that doesn’t have any real teeth in practicality anyway. Instead, all they have to do is move and put the pressure on MLB or the Giants to do something to stop them. My guess is that the most that would happen is that the Giants would file a grievance with MLB, alleging that the A’s violated their territorial rights. MLB would then compel negotiations between the A’s and the Giants to work out some sort of compensation system (sort of like what happened when the Expos moved into the Orioles’ territory back in 2005) and that would be that. Probably, the A’s would agree to give the Giants a percentage of their cable television income along with a large wad of cash up front. But neither MLB nor the Giants would ever file suit in court to enforce the antitrust exemption.
So, in sum, if the A’s want to move, they simply have to make their deal with San Jose and, as the Nike ad says, Just Do It.
Professor of Legal Writing
Villanova University School of Law
299 North Spring Mill Road
Villanova, PA 19085
P.S. You can view my selected writings site and sign up for notification of my new work athttp://works.bepress.com/mitchell_nathanson