Second Order Electoral Rules and National Party Systems

The effect of electoral rules on party systems have been well known since Maurice Duverger first proposed his famous law: that plurality elections tend to result in two party systems and proportional systems tend to multipartism. Most research on electoral rules and party systems has focused on ‘first order’ national elections. Often considered to be ‘second order’ in terms of issues and voting behaviour, European Parliament elections are also held under different electoral rules to national elections. This paper examines the effects that these ‘second order electoral rules’ have on the effective number of parties competing in EP elections. It proposes that where the district magnitude used in European Parliament elections is greater than that used in national elections, the number of parties competing in EP elections will shift over successive elections from the established national level party system towards what we would expect from the EP electoral rules in isolation. Using a combination of Taagepera’s logical quantitative modelling method and multi-level mixed-effects regression, support is found for this theory. The consequence of this finding might suggest that EP elections are becoming decoupled from national level politics. However, further analysis reveals that the size of the EP party system has a feedback effect on the size of the party system at national elections, suggesting that European and national politics are becoming more entwined than ever.