Major league baseball teams may not arbitrarily add drug-testing clauses to player contracts, a federal arbitrator said today.

In making the ruling, Tom Roberts of Los Angeles agreed with the players union by saying that owners may not bypass the union to add such clauses to contracts.

The decision doesn't affect the Baltimore Orioles, who began a program of testing last winter and have everyone on their roster signed up except center fielder Fred Lynn and two players mentioned in last summer's Pittsburgh drug trials.

Those two players are outfielder Lee Lacy and second baseman Alan Wiggins, who were ordered by Commissioner Peter Ueberroth to undergo random tests for the rest of their careers because they were mentioned in the Pittsburgh trials. Roberts said his ruling wouldn't include players involved in the Pittsburgh trials.

The Orioles' program is not affected by the ruling because it was an agreement between players and doctors, and was started by agent Ron Shapiro, not the club.

"Our program was created because of my concern that clauses added to contracts wouldn't hold up under the grievance process," Shapiro said.

Otherwise, the ruling also essentially means that widespread drug testing is once more dead in baseball because the union consistently has maintained that testing is not a way to get drugs out of baseball.

Under the Basic Agreement between players and owners, only benefits may be added to the standard players' contract, and the owners had contended drug testing was a benefit.

"They must go through the union for such an agreement ," said Donald Fehr, executive director of the Major League Baseball Players Association. "Obviously, we are pleased. It was a correct decision. It reaffirms the basic principle that you can't bypass the union. Now, we can go back and negotiate."

Barry Rona, head of the owners' Players Relations Committee, said, "I'm very disappointed by the decision. It's clear the real losers are the players."

Neither Ueberroth nor Roberts was available for comment.