Government Alternation and Legislative Party Unity : The Case of Italy, 1988–2008

The large literature on legislative party unity identifies the confidence relationship, i.e. the threat of being voted out of office and losing agenda setting powers, as well as cabinet membership, as two crucial institutional sources of party discipline. However, by focusing on the dramatic change in the Italian political system following the 1994 election, the article shows that the impact of these factors on party unity (and the direction of this impact) hinge crucially on the possibility of government alternation rather than mere cabinet turnover. This is illustrated by an index of party unity that explicitly focuses on the behaviour of individual MPs derived from a roll-call analysis of the Italian Chamber of Deputies during the period 1988–2008.