La jurisprudencia como instancia creadora de instituciones jurídicas que posteriormente se regulan por ley: a propósito de algunas experiencias en el ámbito del Derecho de consumo

This article examines the role of case law as a creative force in shaping legal institutions that are later incorporated by the legislature into positive law, focusing on two key doctrines in consumer law: contractual incorporation of advertising and the material transparency control. Both originate as judicial constructs developed by the Spanish Supreme Court—later refined by the CJEU in the latter case—and are eventually codified by the legislature in the LGDCU, the LCGC, and the 2019 Real Estate Credit Contracts Act. The study demonstrates that, although case law is not a formal source of law in Spain, it functions as a normative driver by identifying regulatory gaps and anticipating solutions that strengthen legal certainty and contractual balance.