An Institutional Solution to Guarantee Party Unity: The Anti-Defection Law of Israel

According to established wisdom on the relationship between party cohesion and discipline (Bowler et al 1999; Hazan 2003), there is a sequential relationship between the two facets of party unity: parties enter the legislature with a particular degree of cohesion, which, in turn determines the range and degree of disciplinary measures that may be necessary, and possible, to invoke in order to compel legislative party unity. This view, however, is nuanced by the proliferation of anti-defection laws in a number of new and some established democracies. Such laws set out ex ante the penalties for elected legislators who would leave their parliamentary party groups during the legislative term and by do so doing they to ensure a base-line standard of party cohesion and unity, which in turn constrains the applicability of further disciplinary measures. In short, anti-defection laws promise an institutional solution to guarantee or party cohesion and unity. Over the years, legislative and party politics scholars have become increasingly more interested in studying the proliferation of such laws (Janda 2009; Mershon and Shvetsova 2015; Nikolenyi and Shenhav 2015), however, there continues to be a marked lacuna of work assessing if anti-defection laws actually keep parties more united. The central objective of this paper is to assess the impact that Israel’s anti-defection law, passed in 1991, has had on pattern of party unity in the Knesset. The central finding is that while the anti-defection legislation has failed to reduce the number of legislators who leave their parliamentary party group, it has fundamentally changed the types and timing defections: the overwhelming majority of defections since 1991 have been collective, rather than individual, and they have occurred in the last three months leading up to the next general election.