The ability to generate theories of lawmaking has not been matched by an ability to evaluate the success of these theories for explaining legislative reality. The principal problem in testing lawmaking theories is that many analysts use roll-call votes—or various measures based on roll-call votes—when, in fact, these votes are partly a cause and partly a consequence of the very things the theories seek to explain. This can lead to erroneous substantive conclusions and characterizations. I show how embedding the theoretical predictions of the party gatekeeping and veto pivot theories of lawmaking within a statistical model used to estimate ideal points yields a straightforward test; if the gridlock interval measured using votes on policies predicted by the theories is nonzero, the predictions of the theory are not supported by the observed data and assumed behavioral voting model. Implementing the test reveals little support for either theory.