Washington (CNN) -- Baseball all-time home run champion Barry Bonds won a big legal victory Friday when a federal appeals court ruled that evidence the government says would prove he lied about using steroids is inadmissible in court.
The San Francisco-based 9th Circuit U.S. Court of Appeals, in a divided opinion, said the government cannot use urine samples and other evidence in its perjury case against the former San Francisco Giants star.
Bonds was indicted in federal court in December 2008 on 10 counts of making false statements to a grand jury -- specifically, denying that he knowingly took steroids and other performance-enhancing drugs.
His criminal trial has been delayed while the legal issues are being worked out. It was unclear whether the Justice Department will now appeal to the Supreme Court in an effort to allow the evidence to be used in court.
The Appeals Court ruling upholds a February 2009 ruling from U.S. District Judge Susan Illston that there was no proof that positive steroid tests from 2000 and 2001 were Bonds' and that out-of-court statements from his former trainer, Greg Anderson, are hearsay.
The appeals court majority said the repeated refusal of Anderson to testify against Bonds means evidence allegedly gathered by him is considered "inadmissible, since he would be unable to vouch for its authenticity."
Robert Talbot, a professor at the University of San Francisco School of Law said the ruling essentially torpedoes the prosecution's case, which was heavily dependent on evidence and information from Bonds' former trainer.
"There was a link missing here, that the only way to get down to the nitty-gritty that this was from Barry Bonds was using hearsay testimony," Talbot said.
Anderson, he said, "had possession of the evidence and he had that knowledge, and you can't use that knowledge unless he actually testifies under oath."
"To try and prove the case beyond a reasonable doubt, particularly in San Francisco where there are going to be many, many people chosen for a jury who would be behind Barry Bonds -- it should be the death knell," Talbot said.
"Practically speaking they should say, 'We gave it our best shot, and it's just not there,'" he said.
Bonds > The FEDS