Purging the police in nascent democracies

How do new democracies reckon with inherited authoritarian enforcement agencies? Obviously, they can disband these agencies and build new ones (thorough purge) or make former agents work for the new regime (no purge). A third way is to purge selectively: evaluate each agent, case by case. We argue that, even accounting for self-selection, such selective purges are most likely to succeed when agents are moderate in competence and ideology. When the pool of agents is less competent or more loyal to the ancien regime, selective purges give way to thorough purges; when competence and loyalty are high, “no purges” are preferred. This theory is supported with data on the operation of vetting commissions in 49 sub-national regions of Poland. We analyze these data after developing a systematic approach to case selection that builds on the Most Similar Systems Design method, traditionally used for theory building.