The protection of marine environment assumes a special place under UNCLOS. Part XII provides for general obligations to protect and preserve the environment as well as more specific provisions concerning the prevention, reduction and control of marine pollution, including those relating to different sources of pollution. At the same time, Part XII is intended to provide a general framework for the protection of the marine environment. This framework nature is demonstrated not only by the existence of many generally-worded provisions and open-ended obligations which need to be further elaborated but also in the existence of numerous reference to external rules and standards, international organisations and regional arrangements. This chapter examines the contribution of UNCLOS tribunals to clarifying the scope and content of the general obligation to protect and preserve the marine environment before moving to discussing the extent to which UNCLOS tribunals have shed light on the normative content of three key environmental obligations and principles in the context of the marine environment.

The term ‘coastal State’ is not defined under UNCLOS despite being one of the most frequently used terms. In the EEZ, UNCLOS confers upon coastal States both exclusive sovereign rights and jurisdiction over natural resources and jurisdiction in relation to artificial islands, installations and structure, marine scientific research and environmental protection. However, the scope of these rights and obligations is not always clearly set out in the relevant provisions, requiring further clarification and elaboration. Moreover, due to the new scope of power given to coastal States in the EEZ, the question has arisen as to how coastal States’ rights and obligations in this new maritime zone, as well as coastal States’ rights and obligations in the territorial sea and the high seas, interact with historic claims arising prior to the entry into force of UNCLOS. This chapter analyses the decisions rendered by UNCLOS tribunals addressing the abovementioned issues and assesses the extent to which they have contributed to clarifying relevant rules relating to coastal States’ rights and obligations under the law of the sea.

The procedural rules on dispute settlement are primarily contained in Part XV UNCLOS. These rules set out the conditions for UNCLOS tribunals to establish and exercise their compulsory jurisdiction hear contentious disputes. In addition to disputes between States, UNCLOS also grants the Seabed Disputes Chamber advisory jurisdiction pursuant to Article 191 UNCLOS. ITLOS as a full tribunal, however, has also found that it may exercise advisory jurisdiction despite the absence of an explicit provision to that effect under UNCLOS and the ITLOS Statute. This Chapter critically examines UNCLOS tribunals’ decisions relating the conditions for the establishment of compulsory jurisdiction in contentious proceedings under Part XV and the establishment of advisory jurisdiction of both the SDC and ITLOS as a full tribunal, in order to determine the extent to which UNCLOS tribunals have clarified the procedural law under the Convention.

This chapter begins with a brief overview of the UNCLOS dispute settlement system established under Part XV UNCLOS. It then provides a conceptual framework for understanding what is meant by ‘development of the law’ by international courts and tribunals in order to set the stage for an analysis of the development of the law of the sea in the subsequent chapters. The chapter suggests a working definition of the term ‘development of the law’ and explains the ways in which international courts and tribunals ‘develop the law’. In the course of doing so, the chapter also explores the role of legal reasoning in the assessment of the contribution of judicial decisions to the development of international law.

This final chapter first takes stock of the contribution of UNCLOS tribunals to the development of the law of sea, specifically assessing the areas of the law of the sea in which the contribution has been most prominent and the types of contribution that have been made, as well as the interpretative methods that UNCLOS tribunals have employed in the course of deciding their disputes or rendering advisory opinions. With the understanding that UNCLOS tribunals operate within a legal framework with constraints and limitations which impact the way they decide cases and thus the extent which they can contribute to developing the law, the chapter then explores the factors that help explain the decision-making process of UNCLOS tribunals and thus the room available for UNCLOS tribunals to take on the role of developing the law. These factors include the scope of jurisdiction that UNCLOS confers on the tribunals the institutional structure of UNCLOS and the expected and self-perceived roles of UNCLOS tribunals. Finally, the chapter offers some observations on whether there are major differences in the contribution of ITLOS and Annex VII tribunals to the development of the law of the sea.

The rights and duties of flag States go hand in hand under the UNCLOS legal framework. A State bears the right to grant a ship its nationality and is entitled to exercise exclusive jurisdiction over the ship. At the same time, a flag State has the obligation to effectively exercise its jurisdiction and control over the ship sailing under its flag. While the provisions relating to flag States’ rights and obligations are found in Part VII UNCLOS entitled ‘High seas’, their application apply to wherever the ship may find itself. Given the omnipresence of ships at seas, clarity and certainty regarding flag States’ rights and obligations is crucial for the effective implementation of UNCLOS, as well as for ensuring delicate balance between the rights and obligations of coastal States and of flag States upon which UNCLOS hinges. This chapter examines the decisions of UNCLOS tribunals relating to flag States’ rights and obligations, in order to examine whether and to what extent UNCLOS tribunals have contributed to the clarification and development of the relevant rules pertaining to flag States.

This chapter examines UNCLOS tribunals’ contribution to the development of the law on maritime entitlement and maritime delimitation-two distinct but related concepts. The chapter first analyses and assesses the extent to which UNCLOS tribunals—as the first international tribunals to deal with questions relating to the entitlement to a continental shelf beyond 200 nm and entitlement from insular features—have contributed to clarifying the legal ambiguities concerning these two issues. The chapter then analyses UNCLOS tribunals’ decisions relating to maritime delimitation within and beyond 200 nm, with a focus on examining the convergences and divergences in UNCLOS tribunals’ application of the established three-stage approach within 200 nm and on assessing the contribution of UNCLOS tribunals to clarifying the legal ambiguities concerning the delimitation of the continental shelf beyond 200 nm.