In papers filed today (June 21), federal prosecutors said a 1972 U.S. Supreme Court ruling gives the government the right to force two Chronicle reporters, Mark Fainaru-Wada and Lance Williams (both pictured), to divulge their source of a grand jury transcript in the Barry Bonds steroids case. “On a record similar to the one in this case, the court held that the public interest in effective law enforcement outweighed the uncertain adverse effects from requiring those few reporters who have evidence of a crime to give evidence,” wrote Assistant U.S. Attorneys Brian Hershman and Michael Raphael. The government had sought the information from “all reasonable sources” before issuing subpoenas to the reporters. The Chron’s Bob Egelko detailed the new filings on sfgate.com this afternoon. U.S. District Judge Jeffrey White has scheduled a hearing for Aug. 4 on whether to enforce the subpoenas. If the judge decides to enforce the subpoenas, and the reporters may face jail time if they continue to refuse to reveal their source.