Rupert Cornwell: If a dispute is not settled, entire seasons can be lost

Major League Baseball's takeover of the Los Angeles Dodgers is but further proof of the tight, centralised control exerted by the American sports leagues – operating, in some respects almost literally, as laws unto themselves.

The major league US sports – baseball, (American) football, basketball, ice hockey and most recently soccer – are de facto cartels. Since 1922, MLB has been exempt from federal anti-trust laws. The National Football League (NFL), the world's richest sports league and the most popular in the US, enjoys a partial exemption.

In the US, you cannot simply set up a new baseball, football or basketball team and enrol it in MLB, NFL or the National Basketball Association (NBA). There is no promotion or relegation between the major and minor leagues, as in Britain. Occasionally, new expansion franchises are admitted; otherwise, the same teams play each other year after year.

The leagues (to all practical purposes their owners) act together – often imposing some form of revenue sharing or salary caps for players – to ensure nothing disrupts this orderly and usually profitable universe. Hence MLB's swift intervention in the Dodgers, when one of baseball's most famous and valuable franchises is paralysed by its owners' bitter divorce proceedings.

It is not the first such intervention. The ailing Montreal Expos were run by MLB for the 2004 season, before the franchise was moved and they became the Washington Nationals. Last year, the League came close to taking over the Texas Rangers, when the franchise flirted with bankruptcy under former owner Tom Hicks (of Liverpool Football Club fame).

And businesses is what the big sports leagues are, which also makes them theatre of some of America's most contentious labour disputes. In Britain, a shut-down sports league is all but unimaginable. In the US, relations between owners and players are governed by strict collective revenue-sharing agreements. When an agreement expires, a strike or lock-out can occur.

The 2011 NFL season is at risk because of an owners' lock-out of players, and a similar row threatens the NBA. If a dispute is not settled, entire seasons can be lost, as happened with hockey in 2004/2005.