When Loyalty to Policy Matters: Party Affiliation and Policy Change

This paper deals with the phenomenon of legislative party switching and the electoral cost it entails. Assuming that voters tend to favour representatives with loyalty and consistency in policy implementation, scholars have shown that defectors are usually aware of the risk of being penalized by voters, and try to avoid electoral cost. However, not all defections may be perceived as acts of disloyalty. So far, scholarship has not acknowledged the constraints on interparty movements made on policy grounds, where politicians might defect from a party whose policy has ceased to be congruent with its manifesto. Drawing on data of legislative party switching in 15 democracies over the period from 1991–2012, this paper demonstrates that only when voters perceive switching as exhibition of disloyalty, they are willing to impose electoral cost and consequently constrain defection.