The return of institutions to the main research agenda has highlighted the importance of rules in economic analysis. The New Institutional Economics has allowed a better understanding of the case studies that concern different areas of knowledge, also the one concerning the management of natural resources. In this article, the institutional analysis focuses on the maritime domain, where two large civil liability regimes for pollution coexist (OPA 90-IMO), each in a different geographical area (United States - Europe). Therefore, a comparative analysis is made between the two large regimes of civil responsibility assignment applying them to the Prestige catastrophe. In this way, the allocation and distribution of responsibilities in the investigation and subsequent judicial process of the Prestige is compared with an alternative scenario in which the applicable compensation instruments are governed by the provisions of the Oil Polution Act of 1990 (OPA 90), in order to establish a rigorous analysis on the effects that the different norms can have in the same scenario. In the comparative established in the case of the Prestige, where the responsibilities were solved very slowly in a judicial process with high transaction costs, the application of rules governed by the OPA 90 would not count with such a high degree of imperfection. This is so, since by applying the preponderance of the evidence existing in OPA 90 there would be no mitigation for the presumed culprits. On the other hand, the agents involved in the sinking would not be limited only to the owner, but also that operators or shipowners would be responsible as well. In addition, the amount of compensation would increase when counting in the damage count the personal damages, the taxes without perceiving and the ecological damage caused in a broad sense, damages not computable in the IMO.
