"Is Major League Baseball worthy of that antitrust exemption granted at the federal level?" asked Charlie Dent, a Pennsylvania Republican. "All I'm asking is that this issue [steroids] be given the same level of attention and interest by Major League Baseball as the gambling issue. The policy, to many of us, is unacceptable."

Rep. Henry A. Waxman of California, the committee's ranking Democrat, suggested it might be "time for some new leadership in baseball."

Baseball uses the antitrust exemption to pool resources among its teams and engage in other behavior that would not be permitted by other businesses.

A memorandum prepared for the hearing by the committee's Democratic leadership said: "Baseball is a multi-billion dollar industry that enjoys extensive public subsidies, tax breaks and an exemption from antitrust laws. Over the last decade, credible allegations of widespread use of anabolic steroids have cast a cloud over the sport."

Selig testified that the sport has reduced positive tests for performance-enhancing drugs from 5 percent to 7 percent in 2003 to 1 percent to 2 percent in 2004. He praised a testing agreement reached with the players' union in January that , for the first time, includes year-round testing and a 10-day suspension for a first violation.

"I can assure you we're not taking this lightly," the commissioner told the panel.

But committee members said a draft of the new testing protocols indicates that the initial penalty can be either a suspension or a $10,000 fine. Another "loophole" cited by the panel is a provision that the testing policy will be suspended if there is an independent government investigation into drug use in baseball.

Baseball defended the provision by saying it was written to protect players' privacy.

From the beginning of the 11-hour hearing, the committee seemed eager to clarify that it was not on a "witch hunt." Davis, the chairman, characterized the hearing's purpose in broad public policy terms. He said the most important function was to address "the larger societal and public health ramifications of steroid use."

In addition to issuing subpoenas to players, the committee invited two couples who blame steroids for their sons' suicides. The Hootons of Texas and the Garibaldis of California said their sons, one in high school and one in college, were advised by coaches to get bigger. Each family blames steroids for the young men's deaths and says major league stars set a bad example.

"You are cowards when it comes to facing your fans and the kids," said Donald Hooton, his voice rising. He is the father of former high school pitcher Taylor Hooton, who died 20 months ago as he was about to enter his senior year in Plano, Texas. "Why don't you behave like we try to teach our kids to behave?" Hooton asked.

Davis said that Canseco's recent tell-all book - and baseball's initial refusal to investigate its allegations - were instrumental in his decision to convene the session. A former Washington Senators fan, Davis said baseball "misjudged our seriousness of purpose."

Canseco has been the object of scorn within baseball since his book was released last month, claiming to expose "rampant" steroid use in the sport. One witness yesterday, Boston Red Sox pitcher Curt Schilling said he hoped the hearing wouldn't help Canseco "sell more books."

Staff writer Jonathan Pitts contributed to this article.