Litigating Policy Drift: Frozen Categories and Thresholds in Court

The combination of rigid policy rules with shifting political, economic, and social environments can produce drift: policy change without formal modification. We know much about the political origins and consequences of drift but little about the legal battles that accelerate or impede it. I identify two distinct forms of policy rigidity that generate drift: interval freezing and categorical freezing. Drawing from recent and historical cases encompassing voting rights, racial discrimination, religious conscience protections, and other hot-button issues, I argue that drifting policies possess several sources of legal resilience: injuries are difficult to identify; judges can be persuaded of the merits of restraint, textual formalism, and bright-line rules; and policy makers plausibly deny any intentional action in pursuit of controversial outcomes. Drift is not an automatic and unremarkable process of continual policy change but rather the outcome of high-stakes political and legal contestation over how rigid policy thresholds and categories should be adapted to meet shifting conditions.