自1972年的聯合國斯德哥爾摩環境會議以至1992年的里約地球高鋒會以來，國際環境法律的架構歷經了眾所周知的重大擴充與發展。這些發展中的重點之一是宣示了國際社會的所有成員國對於人類社會的某些共同環境議題如全球海洋環境的污染防止，以及瀕臨滅絕物種保護等是承擔著共同的國際法律責任。然而在此高遠的目標之下，吾人所需處理的法律難題在於傳統國際公法的既有原理原則對於個別國家以片面措施執行其領域外的國際環境保護大體是採取負面或保守的立場。針對此一國際法上國家片面執行共同環境保護的法律基礎問題，本文特別析論國際法院在Barcelona Traction一案中所提出，在國際法學界廣為論辯，的Obligation Erga Omnes概念意涵。並進而以此概念意涵的析論為基礎，延伸探討其在現今國際海洋法中對國家執行1982聯合國海洋法公約下的海洋物種保護義務此一重要議題所產生的啟發。總結之處，本文提出Obligation Erga Omnes的意涵延伸已為各別國家執行全球海洋物種保護的片面措施發動上，提供了傳統國際法長期以來所欠缺的一個合理、可引以為據的法律基礎。

It is well-recognized in literature that developments stemming from the 1972 UN Conference on Human Environment (UNCHE), and subsequently the 1992 Rio Earth Summit significantly trans-formed and strengthened the regulatory framework of international environmental law. One major aspect among these developments is the recognition that community of States must undertake common legal responsibility to protect common environment such as the prevention of marine pollution and protecting endangered species. Despite such positive progression in international environmental law, it is nonetheless a well-recognized deficiency that traditional international law does not provide a legal basis for an individual State to take enforcement measures for protecting the environment beyond its national jurisdiction. As regards the problem concerning the legal basis for individual States to take unilateral enforcement measures pursuant to common environment protection such as marine endangered species protection, this article analyses and articulates the significance of the highly controversial concept of obligations erga omnes implied by the International Court of Justice in the Barcelona Traction case. This article then extends the analysis of those legal implications and elaborates how those legal implications relate to the enforcement of obligations for marine endangered species protection under the 1982 UN Convention on the Law of the Sea. Finally, this article concludes that, in terms of unilateral enforcement of marine endangered species protection under the 1982 UNCLOS, legal implications of obligations erga omnes have provided substantial progressions in this regard. As Taiwan becomes more aware of the importance of enforcing the protection of marine environment, those progression suggested by this article should not be overlooked.