Bicameralism Hinges on Legislative Professionalism

Bicameralism is a nearly universal feature of American legislatures, yet its functional impact on legislative outcomes is uncertain. Proponents have claimed that bicameralism would produce better outcomes than unicameralism, as adding a deliberative element prevents the passage of faulty legislation. For bicameralism to work in this fashion, we argue lawmakers must have enough time and resources to meaningfully evaluate legislation produced by the other chamber. We find such behavior is most likely to take place in professionalized state legislatures, evidenced by a lower concurrence rate in the second chamber for bills passed by the first chamber. In state legislatures with less policy capacity, by contrast, the chambers act in a more parallel fashion, dividing the agenda and largely endorsing the other chamber's legislation.