Opposition of Parliamentary Groups and Their Internal (dis)unity – a New Measurement Tool

Abstract

The aim of this paper is to present a way of measuring the actual opposition distance between parliamentary political groups. Attention was focused on opposition observed through the lens of parliamentary group behaviour in potentially final passage votes. The research was conducted on the basis of a case study. The analysis was based on 1524 votes that were taken in the first half of the ninth term of the Polish Sejm. Consideration was given to the degree of opposition between the ruling group and those that formally remained outside the government camp. It was first measured using the Index of Voting Likeness. A new measurement tool was then proposed to quantify the level of opposition between the two groups, taking into account the position of each group on a particular issue, as well as the extent of their internal unity.