Japan is a constitutional monarchy with a parliamentary government. There is universal adult suffrage with a secret ballot for all elective offices. The executive branch is responsible to the Diet, and the judicial branch is independent. Sovereignty, previously embodied in the emperor, is vested in the Japanese people, and the Emperor is defined as the symbol of the state.

Japan's Government is a parliamentary democracy, with a House of Representatives and a House of Councillors. Executive power is vested in a cabinet composed of a prime minister and ministers of state, all of whom must be civilians. The prime minister must be a member of the Diet and is designated by his colleagues. The prime minister has the power to appoint and remove ministers, a majority of whom must be Diet members.

The six major political parties represented in the National Diet are the Liberal Democratic Party (LDP), the Democratic Party of Japan (DPJ), the New Clean Government Party (Komeito), the Japan Communist Party (JCP), the Socialist Democratic Party (SDP), and the Conservative New Party (CNP).

Japan's judicial system, drawn from customary law, civil law, and Anglo-American common law, consists of several levels of courts, with the Supreme Court as the final judicial authority. The Japanese constitution includes a bill of rights similar to the U.S. Bill of Rights, and the Supreme Court has the right of judicial review. Japanese courts do not use a jury system, and there are no administrative courts or claims courts. Because of the judicial system's basis, court decisions are made in accordance with legal statutes. Only Supreme Court decisions have any direct effect on later interpretation of the law.

Japan does not have a federal system, and its 47 prefectures are not sovereign entities in the sense that U.S. States are. Most depend on the central government for subsidies. Governors of prefectures, mayors of municipalities, and prefectural and municipal assembly members are popularly elected to 4-year terms.

Recent Political Developments
The post-World War II years saw tremendous economic growth in Japan, with the political system dominated by the Liberal Democratic Party (LDP). That total domination lasted until the Diet Lower House elections on July 18, 1993 in which the LDP, in power since the mid-1950s, failed to win a majority and saw the end of its four-decade rule. A coalition of new parties and existing opposition parties formed a governing majority and elected a new prime minister, Morihiro Hosokawa, in August 1993. His government's major legislative objective was political reform, consisting of a package of new political financing restrictions and major changes in the electoral system. The coalition succeeded in passing landmark political reform legislation in January 1994.

In April 1994, Prime Minister Hosokawa resigned. Prime Minister Tsutomu Hata formed the successor coalition government, Japan's first minority government in almost 40 years. Prime Minister Hata resigned less than 2 months later. Prime Minister Tomiichi Murayama formed the next government in June 1994, a coalition of his Japan Socialist Party (JSP), the LDP, and the small Sakigake Party. The advent of a coalition containing the JSP and LDP shocked many observers because of their previously fierce rivalry. Prime Minister Murayama served from June 1994 to January 1996. He was succeeded by Prime Minister Ryutaro Hashimoto, who served from January 1996 to July 1998. Prime Minister Hashimoto headed a loose coalition of three parties until July 1998, when he resigned due to a poor electoral showing by the LDP in Upper House elections. He was succeeded as LDP President and Prime Minister by Keizo Obuchi, who took office on July 30, 1998.

The LDP formed a governing coalition with the Liberal Party in January 1999, and Keizo Obuchi remained prime minister. The LDP-Liberal coalition expanded to include the Komeito Party in October 1999. Prime Minister Obuchi suffered a stroke in April 2000 and was replaced by Yoshiro Mori. After the Liberal Party left the coalition in April 2000, Prime Minister Mori welcomed a Liberal Party splinter group, the New Conservative Party, into the ruling coalition. The three-party coalition made up of the LDP, Komeito, and the New Conservative Party maintained its majority in the Diet following the June 2000 Lower House elections. The next Lower House election must be held by June 2004.

After a turbulent year in office, Prime Minister Mori agreed to hold early elections for the LDP presidency in order to improve his party's chances in crucial July 2001 Upper House elections. Riding a wave of grassroots desire for change, political maverick Junichiro Koizumi won an upset victory on April 24, 2001 over former Prime Minister Hashimoto and other party stalwarts on a platform of economic and political reform. Koizumi was elected as Japan's 87th Prime Minister on April 26, 2001. The New Conservative Party dissolved in December 2002, and elements of it and defectors from the opposition DPJ formed the Conservative New Party (CNP). The CNP joined the coalition with the LDP and Komeito at its inception. Prime Minister Koizumi was re-elected as LDP President on September 20, 2003, securing a second 3-year term as Prime Minister. In the fall of 2003, the Liberal Party merged with the Democratic Party of Japan, combining party identification under the DPJ name.