The Endgame of Court-Packing

At several points in history, politicians and commentators have proposed adding seats to the Supreme Court to accomplish partisan ends. We explore the incentives for a political party to initiate “court-packing” and what the Supreme Court would look like in a world where political parties engage in repeated partisan court- packing. To do so, we use an Agent-Based Model and different data sources to calibrate the behaviors of Presidents, Congresses, and Supreme Court justices. We then simulate the future composition of the Court in worlds with and without court-packing. The simulations suggest that a political party with an initial minority of seats on the Court would meaningfully increase the share of years it controls the Court if it were to initiate a cycle of repeated court-packing, especially early on. However, although the number of seats would likely quadruple within 100 years, the simulations suggest there would be only a modest expansion during the likely time horizons of politicians who initiate court-packing. By putting structure on what the Supreme Court would look like in a world with and without court- packing, we hope to generate more careful reflection on the incentives to court- pack and the potential consequences of it.