Abstract
<p>Formally accountable regulation can remain inadequate when its objectives are privately, technically, or distributionally insulated from democratic authorization. This article introduces economic constitutionalism as a second-order framework that extends regulatory legitimacy analysis from the conduct of regulators to the authority to define what regulation is for. The analysis reconstructs authorization assumptions across regulatory legitimacy, capture, public-purpose, and quantification literatures and derives three mechanisms of regulatory-purpose displacement and four design properties for purpose-responsive regulation. Applications to artificial intelligence, platform labor, education, care, and public information demonstrate the framework's comparative diagnostic reach. The argument shifts the regulatory design agenda from procedural compliance alone to the authorization and revision of regulatory purpose.</p>