According to the Principal-Agent Theory, the institutional mechanisms of control are considered key elements to counteract corruption, since they provide relevant information to the principal about the actions of the agent and contribute to increased transparency. Based on this theoretical framework, this paper points to the analysis of an empirical issue: how political corruption via party financing is controlled in the Spanish political system. More specifically, this paper tackles the question of why the successive attempts to counteract corruption through party finance reform have failed. With that aim in mind, special attention is given to both the approval process of the Party Finance Act 1987 and the subsequent unsuccessful attempts of reform during the 90’s. In each specific context, the impact of the various scandals that occurred, as well as the different interests of the actors involved in the process of decision making (the main political parties) are studied. Finally, this paper states that the current lack of consensus that prevents reform in Spain is explained by the loopholes in the existing law, which represents a structure- induced equilibrium in terms of Shepsle. In other words: the status quo remains because ‘not to reform the law’ is a point of equilibrium induced by the Party Funding Act itself, which blocks the consensus between the different parties.