Because they were the defenders of the party government by the House of Representatives and their role in supporting national sovereignty, they never set up a political party within Kizokuin and members who joined a party had to quit the Kizokuin councilor's position based on unwritten rules.
貴族院は、衆議院における政党政治の防波堤となり、国権主義の保持に寄与するという建前上、院内に政党を置くことはなく、政党に参加した議員は不文律として貴族院議員を辞職することになっていた。