The Japanese political system was reformed by the Allied Occupation after 1945 in ways that were intended to democratize the country by removing impediments to democracy and by imposing some new institutions.
At the top on the national level, the emperor is now a ceremonial institution, much like the British monarchy. The institution still has, however, a considerable emotional impact which cannot be totally ignored. The one time when this emotional potential might have been manipulated was when the Showa emperor died in 1989; many of the enthronement procedures for his successor are based in Shinto and could have been used to emphasize the ‘divinity’ of the imperial institution. This was, however, not done to a significant degree although there were those who tried.
Government rests in the cabinet which is controlled by the party or parties which control a majority in the lower House of Representatives. There the prime minister is selected by majority vote and he selects his cabinet. Each party puts forward one candidate for prime minister and the leader of each party is, effectively, the party’s candidate. As is typical in a parliamentary system, the cabinet is responsible to the House of Representatives; that is, if it loses its majority on an important issue, it must hold a new election or resign. At the same time, the individual cabinet members are administrators of their ministries and policy makers together with their colleagues in the cabinet.
As is the case in Britain and other similar parliamentary systems, the lower House of Representatives is the more powerful of the two houses of the Diet (or parliament). It not only selects the cabinet, but it has the power to pass laws over the opposition of the upper House of Councilors if it can amass a two-thirds majority. The House has a limited committee system, compared to the American system. The House is elected for a maximum of four years, but elections are called whenever the government loses its majority or chooses to hold an election. The House is elected by popular vote from electoral districts, each of which return up to five members.
The House of Councilors has less power than the House of Representatives and is meant to act as a break on the potentially more populist and radical lower house. Members are elected for six year terms and half the members are elected every three years. Since it is not directly connected to the cabinet, the collapse of a cabinet or a call for an election in the lower house does not effect this time schedule. The House of Councilors is elected partly on the basis of prefectures and partly from a nation-wide constituency. Since popular recognition rather than political skill is of high value for Councilors, there is a tendency in all political parties to nominate nationally famous individuals. These may be senior politicians, but often include sports heroes, popular entertainment idols or other politically insignificant people.
Beneath the elected levels of government is the bureaucracy. Unlike some countries, being a career bureaucrat in the national government is a most esteemed career. This means that a large percentage of the most able men (and recently some women) head directly into the national bureaucracy. As in any government, the bureaucracy holds considerable power. Since so many very able individuals have entered the bureaucracy over a long period of time, the bureaucracy maintains a very high prestige and a great deal of power. Most policy initiatives originate within the bureaucracy rather than from the elected representatives of the people who lack effective policy planning support staffs.
Below the national level of government is a variety of local institutions. Before World War II, the lower levels of government were largely subordinate to the national government. Governors of prefectures were appointed by the Home Minister and most of the bureaucrats at the local level were employed by the national government. The Allied Occupation changed this structure, giving prefectural, city, town and other levels of government a degree of independence; the object was to increase the bounds of democratic practice and to erect hindrances to authoritarianism. Governors are now elected and prefectural and lower assemblies have real powers which they can and do exercise independently of the central government.
There are limits to this independence, however. The Japanese were never comfortable with police forces which were autonomous and, potentially, unable to work smoothly together across prefectural boundaries. The police were re-centralized after the Occupation ended. Also, as many people moved out of rural prefectures to towns or cities, so prefectures with a rapidly declining population experienced financial difficulties. The central government implemented programs to aid such areas or to build public works of national interest such as high-speed railways and highways. The financial power of the central government thus created ample reason for local governments to accept leadership from the center. Although the legal structure is little changed, power has in effect flowed back to the central government.
There are some video clips (all in Japanese) about the constitution at the website, Bideo ne miro Nihonkoku Kempo (The Japanese constitution on video). This site also has the constitution in Japanese. The website of the International Court Network, among others, has the complete English version of the constitution as well as a brief essay on the constitution