In this paper, I empirically investigate how the openness of political institutions to diverse representation can impact conflict-related violence. Regression discontinuity estimates that exploit plausibly exogenous variations in the number of councillors in Colombian municipalities show that political openness substantially decreases conflict-related violence, namely the killing of civilian non-combatants. Empirical evidence suggests that the lower level of political violence stems from parties with close links to armed groups having greater representation on larger municipal councils. Using data about the types of violence employed by these groups, and government representation, I argue that armed violence has decreased not because of power-sharing arrangements involving armed groups linked to the parties with more political representation, but rather because armed groups with more political power deter other groups from initiating certain types of violence.
