WASHINGTON -- Supreme Court nominee John G. Roberts Jr. worked behind the scenes for a coalition of gay-rights activists, and his legal expertise helped them persuade the Supreme Court to issue a landmark 1996 ruling protecting people against discrimination because of their sexual orientation. Then a lawyer specializing in appellate work, the conservative Roberts helped represent the gay activists as part of his law firm's pro bono work. While he did not write the legal briefs or argue the case before the Supreme court, he was instrumental in reviewing the filings and preparing oral arguments, according to several lawyers intimately...