MOSCOW — Early this month, a young opposition-minded member of the Russian parliament spoke for about 10 minutes at a Capitol Hill conference on U.S.-Russia relations. Back home, it’s as if he was found with the Kremlin plans in his boots, ready to hand them over to the CIA. On Friday, the deputy speaker of the lower house of parliament asked the ethics committee to investigate Dmitri Gudkov. He accused the 33-year-old Duma member of calling for American interference in Russia’s domestic affairs — treachery at its worst here and something President Vladimir Putin often warns against. No doubt Gudkov...