Pivotal Politics and the ideological content of Landmark Laws

The Pivotal Politics model (Krehbiel) has significantly influenced the study of American politics, but its core empirical prediction – that the size of the gridlock interval is negatively related to legislative productivity – has not found strong empirical support. We argue that previous research featured a disconnect between the exclusively ideological theory and tests that relied on outcome variables that were not purely ideological. We remedy this by dividing landmark laws (Mayhew) into two counts – those that invoke ideological preferences and those that do not – and uncover results consistent with Pivotal Politics’ core prediction: the size of the gridlock interval is negatively related to the production of ideological legislation. We also find that the size of the gridlock zone is positively related to the production of nonideological legislation. These results hold up in the face of various sensitivity analyses and robustness checks. We further show that Pivotal Politics explains variation in ideological legislation better than alternative theories based on partisan agenda control.