The constitutionalisation of party unity: The origins of anti-defection laws in India and Israel

In spite of a pronounced increase in the number of states that have adopted anti-defection laws over the past several decades, the literature on party unity in democratic legislatures has paid scant attention to understanding the conditions that lead to the adoption of such restrictive measures on the mobility of elected deputies. This article seeks to fill this gap. The authors provide a simple game-theoretic model to explain the passage of anti-defection measures in India, in 1985, and Israel, in 1991. These two democratic states were among the first to experiment with the constitutionalisation of anti-defection measures. Moreover, their comparison is important because although these laws were adopted under seemingly very different circumstances, they were supported with a strong consensus by both the government party, or coalition, and the opposition. It is argued that the reasons for the passage of the anti-defection laws in these two states were rooted in the strategic consequences of the changes that took place in the format of their party systems. The Indian and the Israeli cases show, respectively, that a dominant party system (India) and a tightly balanced bipolar party system (Israel) provided equally compelling incentives for rampant party switching between government and opposition, which therefore created an incentive for both sides to agree to, and adopt, a strict legislative measure to curb defections.