Navigating Uncharted Waters: The Challenges of Implementing the Marine Biodiversity Treaty Beyond National Jurisdiction

Introduction

The world’s oceans, covering over 70% of the Earth’s surface, represent a vast and critical frontier for biodiversity conservation. Approximately two-thirds of this marine expanse lies beyond the jurisdiction of any single nation, in areas known as the high seas or Areas Beyond National Jurisdiction (ABNJ). These regions, while remote, are integral to global ecological balance, providing essential ecosystem services such as carbon sequestration, oxygen production, and habitat for countless marine species. Yet, these areas have long been vulnerable to overexploitation, pollution, and the impacts of climate change, largely due to the absence of a comprehensive international legal framework for their governance.

The Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (hereinafter referred to as the BBNJ Agreement), adopted on June 19, 2023, marks a historic milestone in addressing these governance gaps. Negotiated under the framework of the United Nations Convention on the Law of the Sea (UNCLOS), the BBNJ Agreement seeks to ensure the conservation and sustainable use of marine biodiversity in ABNJ through international cooperation, addressing issues such as marine genetic resources, area-based management tools, environmental impact assessments, and capacity building.

However, the implementation of the BBNJ Agreement poses significant legal, political, and practical challenges. This article explores the multifaceted obstacles to its effective enforcement, focusing on the legal mechanisms for treaty adoption, the interplay between international and national legal systems, and the implications of foundational international legal principles such as those enshrined in the Vienna Convention on the Law of Treaties (VCLT) of 1969. Given the ambiguity surrounding the specific national context (“this country”), a generalized framework will be applied with hypothetical references to monist and dualist approaches, using illustrative examples where necessary.

The BBNJ Agreement: Scope and Objectives

The BBNJ Agreement is a landmark instrument under UNCLOS, addressing the conservation and sustainable use of marine biodiversity in ABNJ. Its primary objective, as outlined in Article 2 of the Agreement, is to ensure the long-term conservation and sustainable use of marine biological diversity through effective implementation of UNCLOS provisions and enhanced international cooperation (United Nations, 2023a). The Agreement focuses on four key areas: the fair and equitable sharing of benefits from marine genetic resources (MGRs), the establishment of area-based management tools (ABMTs) including marine protected areas (MPAs), the conduct of environmental impact assessments (EIAs), and capacity building and technology transfer (United Nations, 2023a).

Part II of the Agreement, particularly Articles 7 to 16, governs the access to and benefit-sharing of MGRs, aiming to prevent exploitation while ensuring equitable distribution of benefits among states. Part III, spanning Articles 17 to 22, establishes mechanisms for ABMTs, including the designation of MPAs to safeguard critical habitats. Environmental impact assessments, detailed in Part IV (Articles 23 to 33), mandate states to evaluate the potential consequences of activities in ABNJ. Finally, capacity building and technology transfer, under Part V (Articles 34 to 39), address disparities in technical and scientific capabilities among states, ensuring broader participation in the Agreement’s implementation (United Nations, 2023a).

While the BBNJ Agreement provides a robust framework, its success hinges on effective implementation by states, requiring integration into national legal systems, adherence to international obligations, and resolution of jurisdictional and enforcement challenges.

Legal Challenges in Implementing the BBNJ Agreement

Jurisdictional Ambiguities and Enforcement Gaps

One of the foremost challenges in implementing the BBNJ Agreement lies in the jurisdictional complexities of ABNJ. Unlike areas within national jurisdiction, where states exercise sovereignty over their exclusive economic zones (EEZs), ABNJ are governed by the principle of the common heritage of mankind and freedom of the high seas as enshrined in UNCLOS (United Nations, 1982). While the BBNJ Agreement seeks to regulate activities in these areas, it lacks a centralized enforcement mechanism. The absence of a global maritime authority means that enforcement relies on state cooperation and flag state jurisdiction, which can be inconsistent due to varying national priorities and capacities (Gjerde et al., 2023).

For instance, Article 21 of the BBNJ Agreement mandates states to cooperate in the establishment and management of MPAs. However, without binding enforcement powers, compliance may depend on voluntary commitments, leading to potential non-adherence by states with economic interests in activities such as deep-sea mining or overfishing (Wright et al., 2024). This challenge is compounded for developing states, which may lack the resources to monitor or regulate activities in ABNJ effectively, despite obligations under Articles 34 and 35 to build capacity.

Conflicts with Existing Regimes

The BBNJ Agreement must also navigate potential conflicts with pre-existing international and regional frameworks. Fisheries, for instance, are managed by regional fisheries management organizations (RFMOs) under UNCLOS and the United Nations Fish Stocks Agreement (UNFSA). While Article 4 of the BBNJ Agreement emphasizes that it does not undermine existing instruments, tensions arise in delineating its scope vis-à-vis RFMOs, particularly regarding biodiversity conservation versus sustainable fishing (Scanlon, 2025). Recent analyses highlight that integrating fisheries into the broader conservation goals of the BBNJ Agreement remains a contentious issue, risking fragmented governance (Nature, 2025).

Similarly, the International Seabed Authority (ISA), which regulates deep-sea mining under UNCLOS, may face overlapping mandates with the BBNJ Agreement, especially concerning environmental impact assessments under Article 30. Resolving these overlaps will require clear delineation of responsibilities and robust coordination mechanisms, as discussed in recent studies (ScienceDirect, 2025).

Capacity and Resource Disparities

The effective implementation of the BBNJ Agreement is further hindered by disparities in state capacity. Developing countries, particularly small island developing states (SIDS), often lack the technological, financial, and scientific resources to participate meaningfully in activities such as EIAs or benefit-sharing from MGRs. While Part V of the Agreement addresses capacity building, the mechanisms for funding and technology transfer remain under-defined, risking inequitable outcomes (IUCN, 2023). Ensuring compliance with obligations under Articles 34 to 39 will require sustained international support and innovative financing models.

Legal Mechanisms for Treaty Adoption

Entering into the BBNJ Agreement: Legal Provisions

The BBNJ Agreement, as an international treaty under UNCLOS, provides clear mechanisms for states to become parties. According to Article 48 of the Agreement, it is open for signature by all states and regional economic integration organizations at the United Nations Headquarters. Following signature, states must ratify, accept, or approve the Agreement in accordance with their national legal processes (United Nations, 2023a). Article 50 further stipulates that the Agreement enters into force 120 days after the deposit of the 60th instrument of ratification, acceptance, approval, or accession, emphasizing the importance of widespread state participation for its effectiveness.

For a state to legally enter into the BBNJ Agreement, it must adhere to its internal constitutional and legal requirements for treaty-making. This process typically involves executive action (negotiation and signing) followed by legislative approval where required, reflecting the state’s approach to international law—whether monist or dualist—as discussed below.

Monist vs. Dualist Approaches: A Hypothetical Analysis

The integration of international treaties like the BBNJ Agreement into national legal systems depends on whether a state adopts a monist or dualist approach to international law. In a monist system, international law is automatically incorporated into domestic law upon ratification, requiring no further legislative action for enforceability in national courts. By contrast, in a dualist system, treaties must be explicitly transformed into national law through legislative enactment before they can be applied domestically (Crawford, 2019).

Assuming “this country” operates under a dualist framework—a common approach among many common law jurisdictions such as the United Kingdom—ratification of the BBNJ Agreement by the executive would not suffice for its direct application within national courts. Instead, the government would need to introduce domestic legislation to give effect to the Agreement’s provisions, such as establishing mechanisms for EIAs or enforcing ABMTs under national maritime laws. This process could delay implementation and create discrepancies between international obligations and national enforcement capacities. Legislative delays or political opposition could further complicate compliance with time-sensitive provisions, such as those under Article 30 regarding EIAs (Cassese, 2005).

Conversely, if “this country” were a monist state—common in civil law jurisdictions like France—the BBNJ Agreement would become part of domestic law upon ratification, provided it aligns with constitutional norms. This approach facilitates quicker implementation but may raise issues if national courts interpret treaty provisions inconsistently with international intent, particularly on complex issues like benefit-sharing under Articles 7 to 16 (Crawford, 2019). Regardless of the system, ensuring alignment between national laws and the BBNJ Agreement’s objectives requires robust legal and institutional frameworks, often necessitating capacity building as mandated under Part V.

The BBNJ Agreement and the Vienna Convention on the Law of Treaties (VCLT) 1969

The Vienna Convention on the Law of Treaties (VCLT) of 1969 is a cornerstone of international treaty law, codifying rules for the formation, interpretation, and termination of treaties. While the BBNJ Agreement itself is not a “party” to the VCLT—since the VCLT applies to states and international organizations rather than specific treaties—its drafting, adoption, and implementation are informed by VCLT principles as customary international law (United Nations, 1969).

Key VCLT provisions relevant to the BBNJ Agreement include Article 26 (“pacta sunt servanda”), which binds states to perform treaty obligations in good faith, and Article 31, which provides for treaty interpretation based on the ordinary meaning of terms in their context and in light of the treaty’s object and purpose. These principles guide how states negotiate and implement the BBNJ Agreement, ensuring that commitments under Articles 2, 21, and 30 are upheld consistently across jurisdictions (Villiger, 2009).

For other countries entering into treaties with or under the framework of the BBNJ Agreement, the VCLT offers critical guidance. States must ensure that their ratification processes align with Article 11 of the VCLT, which recognizes various means of expressing consent to be bound, such as signature or ratification. Moreover, Article 27 prohibits states from invoking internal law as justification for failing to perform treaty obligations, a principle particularly relevant for dualist states where domestic legislation may lag behind international commitments. This underscores the need for states to harmonize national laws with BBNJ provisions promptly upon ratification (United Nations, 1969).

Additionally, the VCLT’s framework on reservations (Articles 19 to 23) informs how states might engage with the BBNJ Agreement. While the Agreement’s text does not explicitly prohibit reservations, states must ensure that any reservations do not undermine the treaty’s object and purpose, particularly its conservation goals under Article 2. For instance, a reservation excluding certain obligations related to MPAs (Article 21) could be deemed incompatible with the Agreement’s aims, limiting a state’s ability to selectively comply (Villiger, 2009).

Implications for National and International Policy

The challenges of implementing the BBNJ Agreement extend beyond legal frameworks to encompass policy and practical dimensions. At the national level, states must develop coherent strategies to integrate treaty obligations into domestic maritime policies, ensuring alignment with broader environmental and economic goals. For dualist states, this may involve enacting specific legislation for EIAs or ABMTs, while monist states must prioritize judicial training to ensure accurate interpretation of international norms.

Internationally, the BBNJ Agreement necessitates enhanced cooperation through mechanisms such as the Conference of the Parties (COP) outlined in Article 47. The COP is tasked with reviewing implementation progress, facilitating coordination among states, and addressing disputes under Part VII (Articles 55 to 59). However, the effectiveness of these bodies depends on state commitment and resource allocation, highlighting the need for sustained diplomatic engagement (Wright et al., 2024).

Moreover, the VCLT’s influence on treaty practice suggests that states must approach the BBNJ Agreement with transparency and good faith, avoiding reservations or interpretations that could undermine collective conservation efforts. Developing states, in particular, should leverage capacity-building provisions under Part V to advocate for technical and financial support, ensuring equitable participation in the Agreement’s benefits (Gjerde et al., 2023).

Conclusion

The BBNJ Agreement represents a critical step toward safeguarding marine biodiversity in Areas Beyond National Jurisdiction, addressing long-standing governance gaps through a comprehensive legal framework. However, its implementation faces significant challenges, including jurisdictional ambiguities, conflicts with existing regimes, and disparities in state capacity. Legal mechanisms for treaty adoption, whether under monist or dualist systems, further complicate the translation of international obligations into national action, necessitating tailored approaches to ensure compliance.

While the BBNJ Agreement operates within the broader context of international treaty law as informed by the VCLT 1969, its success ultimately depends on state willingness to prioritize conservation over competing economic interests. For other countries entering into or engaging with the Agreement, adherence to VCLT principles offers a roadmap for responsible treaty-making, emphasizing good faith, clear interpretation, and alignment with conservation objectives. As the international community navigates these uncharted waters, sustained cooperation, capacity building, and legal harmonization will be essential to realizing the transformative potential of the BBNJ Agreement.

References

Cassese, A. (2005). International Law (2nd ed.). Oxford University Press.

Crawford, J. (2019). Brownlie’s Principles of Public International Law (9th ed.). Oxford University Press.

Gjerde, K. M., et al. (2023). The BBNJ Agreement: Challenges and Opportunities for Ocean Governance. Marine Policy, 152, 105-112. https://doi.org/10.1016/j.marpol.2023.105112

IUCN. (2023). Policy Brief on the BBNJ Treaty. International Union for Conservation of Nature. Retrieved from online sources.

Nature. (2025). Tensions in Integrating Fisheries into the BBNJ Agreement. npj Ocean Sustainability. https://doi.org/10.1038/s44183-025-00142-5

Scanlon, Z. (2025). Fisheries and the BBNJ Agreement: Bridging the Governance Gap. Ocean Yearbook, 39, 221-240.

ScienceDirect. (2025). Governance of Marine Biodiversity Beyond National Jurisdiction: The BBNJ Agreement and the ISA. Marine Policy. https://doi.org/10.1016/j.marpol.2025.106046

United Nations. (1969). Vienna Convention on the Law of Treaties. United Nations Treaty Series, Vol. 1155, p. 331.

United Nations. (1982). United Nations Convention on the Law of the Sea. United Nations Treaty Series, Vol. 1833, p. 3.

United Nations. (2023a). Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction. General Assembly Resolution, A/CONF.232/2023/4.

Villiger, M. E. (2009). Commentary on the 1969 Vienna Convention on the Law of Treaties. Martinus Nijhoff Publishers.

Wright, G., et al. (2024). Implementing the BBNJ Agreement: Legal and Policy Challenges. American Journal of International Law, 118(2), 201-220. https://doi.org/10.1017/ajil.2024.9