PHOENIX — A new lawsuit charges that thousands of Arizonans are illegally being denied the right to vote in federal elections. Legal papers filed Tuesday in federal court here acknowledge that state law requires would-be voters to produce certain identification when registering. That requirement has been upheld in prior court rulings. But attorneys for the League of United Latin American Citizens and the Arizona Students Association point out that the U.S. Supreme Court has said that state law does not — and cannot — prevent people from registering to vote for federal elections using a federally approved registration form. And...