The Legislative branch organ of Japan is the National Diet. It is a bicameral legislature, composing of a lower house, the House of Representatives, and an upper house, the House of Councillors. Empowered by the Constitution to be "the highest organ of State power" and the only "sole law-making organ of the State", its houses are both directly elected under a parallel voting system and is ensured by the Constitution to have no discrimination on the qualifications of each members; whether be it based on "race, creed, sex, social status, family origin, education, property or income". The National Diet, therefore, reflects the sovereignty of the people; a principle of popular sovereignty whereby the supreme power lies within, in this case, the Japanese people.
The Diet responsibilities includes the making of laws, the approval of the annual national budget, the approval of the conclusion of treaties and the selection of the Prime Minister. In addition, it has the power to initiate draft constitutional amendments, which, if approved, are to be presented to the people for ratification in a referendum before being promulgated by the Emperor, in the name of the people.The Constitution also enables both houses to conduct investigations in relation to government, demand the presence and testimony of witnesses, and the production of records, as well as allowing either house of the Diet to demand the presence of the Prime Minister or the other Minister of State, in order to give answers or explanations whenever so required.The Diet is also able to impeach Court judges convicted of criminal or irregular conduct. The Constitution, however, does not specify the voting methods, the number of members of each house, and all other matters pertaining to the method of election of the each members, and are thus, allowed to be determined for by law