According to Kizokuin-rei (the House of Peers Act) in 1889, the privilege of entering the House of Peers was accorded to all the dukes and marquises aged 30 and over, and others who were elected by mutual vote.
1889年貴族院令により30歳以上の公爵・侯爵は全部、ほかは互選で貴族院議員になる特権を有した。