In a move that could have major implications in the doping scandal related to the Bay Area Laboratory Co-Operative (BALCO), the U.S. Anti-Doping Agency has begun to argue that the stringent burden of proof standard known as "beyond a reasonable doubt" should no longer apply to track and field drug cases because of recent changes in anti-doping rules, according to a June 1 memorandum The Washington Post has seen.

USADA Director of Legal Affairs Travis T. Tygart wrote to the agency's Anti-Doping Review Board that the lesser standard of "comfortable satisfaction of the . . . hearing body" should be adopted in the arbitration of all track and field cases initiated after March 1 of this year regardless of when the alleged violations took place.

The matter is significant given the uniqueness of the cases related to the BALCO scandal. For the first time, anti-drug officials are attempting to sanction athletes who haven't failed traditional drug tests. USADA officials will rely on circumstantial evidence seized in a raid of the laboratory last fall and they will deal with, in some cases, powerful teams of lawyers as athletes try to preserve their eligibility for the 2004 Olympics.

Several lawyers contacted last week said USADA's interpretation of the application of the new rules would be hotly contested. Tygart wrote that the lesser burden of proof standard should take effect because the international governing body of track and field (IAAF) on March 1 adopted the World Anti-Doping Code, which last year set "comfortable satisfaction" as the universal standard in doping cases.

Attorneys for 100-meter world record holder Tim Montgomery, one of four U.S. athletes notified of possible drug violations by USADA last Tuesday, said they would dispute the new standard of proof if Montgomery were formally charged.

"I have said many times throughout the week that if Tim Montgomery is subject to a fair process, he doesn't have any worries," said Cristina Arguedas, Montgomery's lead attorney. "When I hear they have changed from a standard of proof called 'beyond a reasonable doubt' to something I've never heard of called 'comfortable satisfaction,' I think that is terribly unfair."

Tygart declined to comment on the memo or respond directly to lawyers' comments, but he defended USADA's protocols.

"The entire process was approved by athletes and approved by the [U.S. Olympic Committee]," Tygart said in a telephone interview. "Our process has really been the platform for the WADA code, which the entire sporting world and governments have signed off on, and those entities have agreed this is fair not only for clean athletes, but also for athletes going through that process."

According to lawyers, "comfortable satisfaction" is commonly used in sports doping cases and is considered essentially the equivalent of the "clear and convincing" standard used in U.S. courts. That standard falls between the low "preponderance of the evidence" standard used in many civil cases, and the strict "beyond a reasonable doubt" applied in criminal cases. Lawyers said "comfortable satisfaction" has been used in international doping cases at least since the 1996 Summer Games in Atlanta.

Besides Montgomery, Chryste Gaines, Michelle Collins and Alvin Harrison received notification letters from USADA. Once they respond in writing by Friday to the agency's Anti-Doping Review Board, which is made up of unidentified medical, technical and legal experts appointed by USADA Chief Executive Officer Terry Madden, USADA will decide whether to press forward with formal charges.

If USADA brings formal charges, the cases would be directed to the Court of Arbitration for sport, which adheres to the rules of the governing international federation -- in this case, the IAAF. In a typical arbitration, arbitrators discuss the rules and how they will be applied after hearing arguments from both sides.

Brian Getz, the attorney for Collins, said USADA raised the issue of standard of proof during a meeting with him and Collins in Dallas on May 23.

USADA said the reasonable doubt standard "would not be applied," Getz said. "Well, we'll see. It's going to be a battleground."

Tygart acknowledged in the memo that "substantive" aspects of the doping rules such as banned substances and sanctions were not generally applied retroactively to conduct, but he said burden of proof fell into a different category, describing it as a "procedural" rule. Such rules apply to all cases initiated after the rule's adoption regardless of when the conduct took place.

Howard Jacobs, one of Montgomery's lawyers, and other attorneys involved in the case said they disagreed with Tygart's interpretation, calling burden of proof a "substantive issue."

"USADA has repeatedly said they were going to use a beyond a reasonable doubt standard . . . now they are changing the standards because they know that the facts and [information] they have does not meet that standard," an attorney who requested anonymity wrote in an e-mail.

The burden of proof is likely to be just one of a number of contested legal issues as attorneys not only seek every advantage for their clients but also strive to put in place the basis for filing suit in U.S. court should they lose in arbitration. In another June 1 memo to the Anti-Doping Review Board that The Post has seen, Tygart stated that "it is beyond question that the formal rules of evidence do not apply to arbitrations," another point lawyers say they will challenge.

Many of the documents seized in the BALCO raid -- such as coded calendars that appear to show drug use -- cannot be fully explained by USADA, which has been unsuccessful in persuading BALCO owner Victor Conte Jr. to act as a witness. How those documents are handled by the arbitrators could be crucial to the cases.

"I don't have a problem with circumstantial evidence," Arguedas said. "It can be persuasive . . . [but] if a handwritten calendar with codes is evidence offered against you, you should be able to question the person that made the notes and challenge the person that made the notes. If you cannot do this, it's not a fair process."