By Dan Levine SAN FRANCISCO - Baseball slugger Barry Bonds' conviction of obstructing justice during a government probe into steroid use was overturned by a U.S. appeals court on Wednesday. The case involved testimony Bonds gave to a grand jury in 2003 about whether he used steroids to help him bash more long balls. Bonds told grand jurors about his childhood when asked whether his former trainer, Greg Anderson, had given him self-injectable substances. In a ruling on Wednesday, the 9th U.S. Circuit Court of Appeals in San Francisco said Bonds gave "a rambling, non-responsive answer to a simple question." Prosecutors did not provided enough evidence that his statement was material to their investigation, the court ruled, and the conviction must be overturned.