Six of baseball's biggest stars made emotional opening statements Thursday at a congressional hearing investigating Major League Baseball's new drug-testing policy and steroid abuse in the game.

Active big-leaguers Sammy Sosa, Curt Schilling, Frank Thomas and Rafael Palmeiro, as well as retired sluggers Jose Canseco and Mark McGwire, were subpoenaed last week to appear Thursday before the House Government Reform Committee in Washington, D.C.

After Canseco briefly addressed the Committee, Sosa, via a translator, said that he has never used steroids during his opening statement.

McGwire slammed allegations made by Canseco in his recently published book that he injected McGwire with steroids while they were teammates. McGwire did not say whether he used steroids during his career and said he won't "participate in naming names" of players who used steroids.

In his opening statement, Palmeiro said emphatically that he has never used steroids and took Cancesco to task for claiming he saw Palmeiro take steroids while they were teammates.

Like McGwire and Palmeiro, Schilling slammed Canseco, saying his claims "should be seen for what they are: an attempt to make money at the expense of others."

Testifying by close-circuit TV, Thomas said he never took steroids.

Commissioner Bud Selig, players' union head Donald Fehr and other baseball executives will also testify.

In beginning Thursday's hearing, Representative Tom Davis (Republican, Virginia) the Chairman of the Committee, implored baseball to "not simply turn its back on recent history, pronounce that the new testing policy will solve everything, and move on."

"You can't look forward without looking back," added Davis.

Davis then went on to scold players and baseball officials for not being co-operative with the Committee.

"Major League Baseball and the players' association greeted word of our inquiry first as a nuisance, then as a negotiation, replete with misstatements," said Davis.

"I understand their desire to avoid the public's prying eye. ... But I think they misjudged our seriousness of purpose. I think they misjudged the will of an American public who believes that sunshine is the best disinfectant."

Representative Henry A. Waxman (Democrat, California), the Committee's ranking minority member, echoed Davis's comments.

"There is a pyramid of steroid use in society and today our investigation starts where it should– with the owners and players at the top of that pyramid," Waxman said.

Davis warned the "hearing will not be the end of our inquiry, far from it. Nor will Major League Baseball be our sole or even primary focus. We're in the first inning of what could be an extra-inning ball game. This is the beginning and not the end."

A spokesman for Representative Davis told CBC Sports Online that players who testify at the hearing do not face criminal prosecution.

Instead, Thursday's hearing serves as an investigative review of baseball's recently instituted drug-testing policy. White also explained the hearings give Congress "a chance to shine some light on what it thinks is an important public health issue."

However, the belief is that players who testify would leave themselves open to potential criminal charges sometime in the future.

Canseco tried to get immunity in exchange for his testimony, but the Committee refused to give immunity to any of the players.

In response, Canseco's lawyer said the former big-league slugger will invoke his Fifth Amendment right to refuse to answer questions that would incriminate him when he testifies.

Representative Mark Souder (Republican Indiana) warned players against pleading the fifth, saying it would be a "terrible tragedy."

Major League Baseball's steroid testing program was criticized in past years as being too lenient, but a new testing plan introduced this year calls for tougher penalties. A first-time offender will be suspended for 10 days. Second-time offenders will be suspended for 30 days. Third-time offenders will be suspended for 60 days. Fourth-time offenders will be suspended for one year.

All suspensions are without pay.

Under the new plan, every player will undergo at least one unannounced test on a randomly selected date during the playing season. There is no specific limit on the number of tests to which any player may randomly be subjected, and players are subject to random testing during the off-season.

Selig and MLB executive Sandy Alderson defended baseball's drug policy in a prepared statement released prior to Thursday's proceedings.

"Some have suggested that greater penalties, particularly for first offenders, would be in order," the statement read. "With the guidance of my medical advisors, however, I agreed to the lesser penalties on the theory that behaviour modification should be the most important goal of our policy and that the penalties in our new policy were well-designed to serve that goal."