Two San Francisco Chronicle reporters subpoenaed to testify before a federal grand jury about how they got Barry Bonds' leaked testimony urged a judge on Wednesday to let them off the hook. The Chronicle's Mark Fainaru-Wada and Lance Williams, the latest reporters to become entangled in the federal government's ramped-up efforts to investigate leaks, argued that the First Amendment protects reporters and their sources. In an affidavit accompanying their filing, Pulitzer Prize-winning journalist Carl Bernstein wrote U.S. District Judge Martin Jenkins of San Francisco that anonymous sources were instrumental in breaking the Watergate scandal.