In ancient times, any noble ranked higher than Chunagon (vice councilor of state) was entitled to do Kanso (submission of a report to the Emperor), but after the reign of Emperor Daigo, the post eligible for Kanso became limited to certain Shikiji-kugyo (high-ranked nobles engaged in submission of reports to the Emperor) who were ranked higher than Dainagon (chief councilor of State) and designated by imperial decree as 'Kanso-kojisha' (literally, attendants in charge of submission of reports to the Emperor), so that even ministers were not allowed to do Kanso unless they were so designated by imperial decrees.
古くは中納言以上の公卿であれば官奏を行い得たが、醍醐天皇以後には宣旨によって指名された大納言以上の特定の公卿が「官奏候侍者」とも称される職事公卿として専らこれを行うようになり、大臣と言えども天皇の宣旨を受けない限りは官奏を行い得なかった。