The lawsuit - filed in federal court in San Jose - is disputing MLB's exemption to federal antitrust law, which MLB has used as a "guise" to control the location of teams, according to the suit.
"It's time for someone to take on this supposed baseball exemption from antitrust laws," said attorney Phil Gregory of Cotchett, Pitre & McCarthy, the law firm representing the city. "The City of San Jose is a perfect candidate to make that challenge."
The San Francisco Giants have objected to the A's potential move on grounds they relied on territorial rights to the San Jose-area market when they built their ballpark, AT&T Park.
The A's say those rights were only meant to support the Giants' failed efforts in the early 1990s to build a San Jose-area ballpark themselves.
MLB Commissioner Bud Selig appointed a committee more than four years ago to study the potential move.
He rejected a proposal earlier this year from San Jose Mayor Chuck Reed to sit down and talk about the A's plans and said Reed's reference to additional litigation at the time was "neither productive nor consistent with process that the Athletics have initiated under our rules."
Major League Baseball spokesman Pat Courtney declined to comment. A's owner Lew Wolff released a brief statement.
"I have no details," Wolff said. "However, I am not in favor of legal action or legal threats to solve business issues."
Wolff has said he is focused on a new stadium in San Jose rather than a move outside the Bay area. Wolff is allowed to consider other sites within the A's territory - such as downtown Oakland - but approval from MLB would be needed for a move outside the territory.
The A's current stadium is run down. A sewage problem forced the A's and Seattle Mariners to use the same locker room after Sunday's game.
The pipes backed up on the lower levels of the stadium, creating a stink and pools of water in the clubhouses used by both teams and the umpires.
Gregory said Wolff is not involved in the lawsuit.
Baseball's antitrust exemption was granted by the U.S. Supreme Court in 1922, with the court ruling that baseball is not interstate commerce.
While baseball may have started as a local affair, it is "squarely in the realm of interstate commerce," the lawsuit contends.
"MLB clubs ply their wares nationwide, games are broadcast throughout the country on satellite TV and radio, as well as cable channels and MLB clubs have fan bases that span from coast to coast," the lawsuit says.