The budget of the United States executive branch is roughly 500 times greater than that of the judicial branch. The executive workforce is more than fifty times greater. How do these enormous disparities affect the practical ability of courts to police executive power? Our judicial capacity model of Supreme Court decision making is the first attempt to take this question seriously. Briefly, in most executive power domains, the limits of judicial capacity create strong pressure on the Supreme Court to adopt hard-edged categorical rules, defer to the political process, or both. The reason is straightforward. In these domains, a departure from deferential or rule-based decisions would invite more litigation than the Court could handle without sacrificing minimum professional standards.
Our model explains why the Supreme Court has historically deferred to congressional delegations of power and avoided interfering with presidential administration, despite significant ideological temptations to intervene. It also explains the few areas of executive power in which the Court has been willing to act aggressively, as well as the one area in which the Court has employed indeterminate standards—as opposed to categorical rules—to invalidate government action. In so doing, the judicial capacity model clarifies when, if at all, it is sensible to urge the courts to constrain executive power in future cases. Finally, the judicial capacity model sheds light on some of the most significant issues in constitutional theory, including judicial competence, judicial independence, and the formalist-functionalist divide over separation of powers. For all of these reasons, judicial capacity deserves a central place on the agenda of executive power scholarship and constitutional theory more generally.