The First Amendment guarantees Atlanta Braves reliever John Rocker the right to free speech. What it doesn't give him is the right to be a ballplayer.

Rocker was ordered to undergo psychiatric testing after he was quoted in a magazine denigrating blacks, foreigners and gays. Commissioner Bud Selig is waiting for those test results before deciding whether to suspend or fine the 25-year-old left-hander.

While few support Rocker's opinions, some have defended his right to express them based on the First Amendment's guarantee of free speech. But the First Amendment -- "Congress shall make no law ... abridging the freedom of speech" -- won't help Rocker.

Its message, honed over two centuries, is that while the government can't stop you from speaking your mind, the Constitution provides no shield in the private sector.

"The First Amendment only applies to state action. This isn't state action," said Harvard Law School professor Paul Weiler, who's planning to place Rocker alongside former Cincinnati Reds owner Marge Schott in the next edition of his casebook. "In terms of the law, his prospects are not great."

That's why private golf clubs are still allowed to discriminate in ways that a public one could not. And that's why Rocker might be immune if he was a pitcher at a public university, or a boxer licensed by the state.

In major league baseball, though, he's fair game.

Rocker saved 38 games for the Braves last year. But he created a personal rivalry with the city of New York during the NL Championship Series, calling Mets fans "stupid" and accusing them of throwing batteries and insulting his mother.

He went even further in a Sports Illustrated article last month, saying he would never play for a New York team because he didn't want to ride a train "next to some queer with AIDS." He bashed immigrants, saying "How the hell did they get in this country?" He also called a black teammate a "fat monkey," spit on a toll machine and mocked Asian women.

Rocker later apologized and said he is not racist.

The Major League Agreement gives the commissioner the power to punish any act considered "to be not in the best interests of the game of baseball." Other commissioners have similar best-interests powers; some, such as those in the NHL, NBA and PGA, also have the specific authority to punish players or employees for speech detrimental to the league or sport.

That's why the First Amendment couldn't protect Denver Nuggets guard Mahmoud Abdul-Rauf when he refused to stand for the "Star-Spangled Banner," saying that to do so would conflict with his Muslim beliefs. NBA rules required every player to "stand respectfully" during the national anthem, and Abdul-Rauf eventually found a way to do so without compromising his beliefs.

And that's why the First Amendment couldn't protect Schott, suspended from baseball for racist comments about blacks and Jews. Or then-Miami Dolphins linebacker Bryan Cox, who was fined for making an obscene gesture at Buffalo fans after enduring what he said was racial abuse.

And that's why the First Amendment won't protect Rocker, either, though the collective bargaining agreement can send the matter to an independent arbitrator.

As the great jurist Oliver Wendell Holmes once wrote: "A policeman may have a constitutional right to talk politics, but he has no constitutional right to be a policeman."

More than 100 years later, the kernel of truth remains.

No one can lock Rocker up for saying what he wants. But the fans can refuse to go to his games, and -- if that concerns them -- teams can refuse to sign him and the league can ban him or take any other action the commissioner deems to be in the best interest of baseball.

A baseball player may have a constitutional right to talk politics, but he has no constitutional right to be a baseball player.