SAN FRANCISCO — A divided federal appeals on Friday court dealt the federal government a significant setback in its prosecution of Barry Bonds on perjury charges.

The 9th U.S. Circuit Court of Appeals ruled Friday that prosecutors may not present positive urine samples and other vital evidence that the government says shows that the slugger knowingly used steroids.

The appeals court ruling upholds a lower court decision barring federal prosecutors from showing the jury any evidence collected by Bonds' personal trainer Greg Anderson.

Anderson last year told the trial court judge that he would rather go to jail on contempt of court charges than testify against Bonds.

The court says evidence tied directly to Anderson is inadmissible "hearsay" evidence unless the trainer testifies to the items' authenticity.

Prosecutors argued that Anderson had told BALCO vice president James Valente that the samples belonged to Bonds and that they would call Valente to the witness stand. But the appeals court said that because Anderson wasn't directly employed by Bonds — the judges considered him an independent contractor — the trainer would need to testify because Bonds didn't control of the samples.

The court noted it was Anderson's idea to collect the urine samples and deliver them to BALCO.

"There is little or no indication that Bonds actually exercised any control over Anderson in determining when the samples were obtained, to whom they were delivered, or what tests were performed on them," Judge Mary Schroeder wrote for the majority court.

Judge Carlos Bea dissented, writing that he would have allowed Valente to testify about the samples.

Although the ruling eliminates what prosecutors said were three positive steroid tests, they still have a fourth test showing Bonds used steroids. In 2003, Major League Baseball tested all of its players for steroid use. The results of those tests were to remain confidential and were to be used only to determine if MLB had a drug problem that needed to be addressed.

The lab that MLB hired to conduct its testing found that Bonds tested negative for steroid use. But in 2004, federal agents seized Bonds' urine sample and had it retested for the designer steroid THG, which they said turned up positive.

Bonds has pleaded not guilty to charges that he lied to a grand jury in December 2003 when he testified that he never knowingly used performance-enhancing drugs. A federal grand jury indicted him in 2007. His trial was scheduled to begin March 2, 2009, but the trial was delayed by the government's appeal.

Unless federal prosecutors asks the Supreme Court to take the case or the appeals court to reconsider its ruling, the case will be sent back to Illston's trial court to reschedule the start of the trial.

Legal experts said it may take Illston several weeks to clear her busy calendar for the Bonds trial. Bonds also has six prominent lawyers with many clients each and their calendars will also have to be taken into consideration as well.