The Diffusion of Power in the Diet

Mikitaka Masuyama

Hogaku Kenkyu: Journal of Law, Politics and Sociology. Vol. 78, No. 11. 2005, pp. 64-86.


Since the 1990s the Liberal Democratic Party has become unable to maintain a stable majority in the Japanese Diet. Although there is an extensive literature on the recent party realignment, little attention has been paid to the consequence in terms of the legislative interaction that profoundly affected the way in which representative democracy works under the Japan's parliamentary cabinet system. This paper fills the gap in the literature by exploring the institutional and political conditions that have determined the degree of power dispersion in the Diet, focusing on its legislative consequence in the 1990s. In an attempt to account for the interparty interaction that may or may not have an impact on the likelihood of a party to support government legislation, I apply a heteroskedastic probit model of legislative support to the data set of government legislation from major postwar Diet sessions. The evidence presented in this paper suggests that, with the exception of the Communists, the opposition parties became fully supportive of government legislation once after the LDP lost its majority in the House of Councilors in 1989. Negotiations between political parties became an essential element of the lawmaking process, and the parties of centrists and social democrats came to play a pivotal role in coalition building, shifting the range of government legislation in their favor. This implies that the diffusion of parliamentary power since the early 1990s has significantly eroded the ability of citizens to know who is responsible for lawmaking and to use elections as instruments of government accountability.