In this article, we demonstrate that changes in the partisan orientation of a country's executive branch influence the likelihood that the government of that country complies with international legal commitments aimed at integration of capital markets. We argue that relative shifts in executive partisan orientation, whether toward the left or toward the right, represent important shifts in national preferences that have heretofore been absent from statistical models of treaty compliance. Using a matching estimator combined with a genetic algorithm to maximize balance in our sample, we show that the causal impact of a state signing Article VIII of the IMF Articles of Agreement is conditioned by right-to-left shifts in partisan orientation. The evidence indicates that such preference changes reduce the constraining effects of Article VIII but also indicates that Article VIII continues to exercise significant causal effects even in the face of relative shifts in executive partisan orientation. © The IO Foundation 2009.