When Cartels Split: Roll Call Votes and Majority Factional Warfare in the Mexico City Assembly

Abstract

This paper reports work in progress. Procedural cartel theory (Cox and McCubbins 2005) expects intra-majority party conflict in final passage votes to be reduced to a minimum. This is a consequence of agenda control by key party members. I inspect roll call voting in the 4th legislature of Mexico City's Assembly (2006-09) uncovering a frequent majority party split in the floor. Ideal point estimation reveals two lines of Assembly cleavage, one the classic left-right divide on economic issues, the other mostly related to appointments of officers at different levels. While the left-leaning PRD majority showed cohesion in the first dimension, the presence of two distinct factions is manifest in the second. The paper suggests that further research should blame rigid assembly rules combined with an unexpected defeat in the 2006 presidential race for this anomaly.