The Giants are claiming nebulous "territorial rights" to the San Jose market, and on that basis are attempting to push the A's much further away entirely out of the Bay Area market. The A's have been waiting for a decision from Major League Baseball for at least four years in this matter but none has been forthcoming.
Now at least one San Jose official is preparing to take the Giants to task on this issue. The Giants stayed in San Francisco moving from Candlestick Park and into brand new Pac Bell Park in 2000. (now AT&T Park) It has been long thought that their fan base does not come from the San Jose area which is additional ammunition for a potential lawsuit. Many years ago, the Giants had seriously looked at San Jose as their potential new home.
In 2010, San Jose Mayor Chuck Reed said that his city would gain the voter's approval to move forward and build a baseball only stadium near the downtown area. However since that proclamation, there has been no official movement in that direction, and now City Concilman Sam Liccardo says it's time to start looking into legal action. Liccardo represents the San Jose area politically and it is thought by many that a proposed suit against the Giants would force all sides to the table by testing Major League Baseball's anti-trust exemption. Liccardo said he would use a legal team that would only be compensated out of a "future settlement" eliminating any potential financial burden for the taxpayers.
While the Dodgers, Red Sox and Cubs play in much older venues, the home of the Oakland Athletics (The Colisuem) was built in the mid-60's and is becoming outdated. When the Oakland Raiders of the NFL returned to the Colisuem in 1996 after 14 seasons in Los Angeles, the stadium was given many much needed upgrades yet still falls far short of today's coveted luxury standards.
Additionally, the Raiders and A's are the final two teams in professional football and baseball that continue to share the same venue. This creates a myriad of issues in addition to overusage of the playing surface every August, September and October which is a detriment for both teams.
Source: CBS - S.F. Bay Area