The Legitimacy Trap: How Regulators' Credibility‐Building Constrains Responsiveness Under Politicization

ABSTRACT This article develops an analytical framework for understanding regulators' struggles for legitimacy, highlighting tensions between two key sources: credibility and responsiveness. A regulator must earn credibility with actors around the regulatory arena, but organizational tools for credibility‐building, including codified rules and mobilized expertise, create path dependence that limits subsequent responsiveness to public pressure. This self‐constraining mechanism generates a “legitimacy trap”: credible regulators become unable to respond without damaging established credibility yet risk organizational survival if they remain unresponsive. I demonstrate this mechanism through process tracing of drug funding policies by England's National Institute for Health and Care Excellence. The findings show how regulators strive to maintain credibility despite partial yet substantial changes signaling responsiveness to public concerns. They reveal why non‐majoritarian institutions resist policy change under politicization and why changes, when forced, involve subsuming new rules within the existing framework, demonstrating the limits of politicization in transforming regulatory policies.