The decline of incrementalism in U.S. lawmaking

Punctuated equilibrium theory (PET) posits that policy change is incremental for long periods of time with occasional shifts in problem definition and governing authority that produce large changes. Incrementalism results from shared norms and standard operating procedures within policy subsystems. The U.S. Congress experienced a series of institutional changes in the 1990s that both introduced more partisanship into subsystem interactions and made it easier for majority party leaders to enact their agenda. These changes have disrupted many of the processes that produce incrementalism. Using data from 1949 to 2022, I find that U.S. policy outputs, measured through public laws, have experienced fewer incremental changes from one term to the next and more moderate and very large changes since 1995. The shift in outputs has been driven primarily by increased partisan conflict within congressional committees. This study highlights the utility of using the stochastic process approach to compare distributions of outputs across time and not only across countries or institutions.