Toga Party: the political basis of judicial investigations against MPs in Italy (1983–2013)

Scholars agree that ideology affects judicial decision-making. We demonstrate that this proposition holds true even when the judiciary is independent of political control. Focusing on Italy (1983–2013), where the politicisation of the judiciary was an issue well before the entry of Berlusconi into politics, we estimate judicial orientations according to the support for factions within the National Judiciary Association. The results show that ideology affects trial court activity against deputies. As the support for left-wing factions increases, prosecutors are more likely to investigate right-wing parties. Conversely, as the share of right-leaning factions grows, investigations of moderate or rightist parties decrease.