Two Birds, One Bill: How BBNJ National Legislation Can Tackle UNCLOS Deep Seabed Mining Gaps

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 (BBNJ Agreement) will enter into force on 17 January 2026, marking a pivotal moment for marine conservation, global ocean governance and multilateralism. Many States Parties will need to pass national laws to implement it. We argue this presents an opportunity to close a related UNCLOS gap: lack of domestic law prohibiting unauthorised deep seabed mining (DSM) by national actors. Part XI of UNCLOS applies this prohibition to all States parties, their nationals and legal entities under their jurisdiction, but the prohibition has not been well-reflected in domestic laws. This matters more than ever today, as the threat of unauthorised DSM looms large. Killing two very closely related birds (BBNJ and DSM) with one legislative stone would strengthen treaty compliance, promote systemic integration between international law regimes, deter unlawful activities, and enable enforcement against rogue actors.

BBNJ Agreement Legislative Wave

The BBNJ Agreement applies to areas beyond national jurisdiction (ABNJ), i.e. the high seas and the seabed beyond national jurisdiction (known as ‘the Area’). The BBNJ Agreement covers four main topics: marine genetic resources, area-based management tools, environmental impact assessments, and capacity-building and transfer of technology. It does not cover DSM in the Area, as that is exclusively governed by Part XI of UNCLOS and the 1994 Implementation Agreement.

The BBNJ Agreement’s rapid 60-State ratification, entering into force only two years after opening for signature, signals strong global commitment to ocean protection. 

In some jurisdictions, ratification gives the treaty direct domestic effect; in others, legislation is required (see: Policy brief on BBNJ Implementation). BBNJ lawmaking has already begun in certain jurisdictions (see: EU Parliament and Council and the United Kingdom). This legislative process, over three decades after UNCLOS entered into force, offers a once-in-a-generation opportunity to strengthen domestic implementation of UNCLOS, plugging gaps that could undermine BBNJ effectiveness, and promoting legal coherence. Without broader alignment with other ABNJ governance, national adoption of BBNJ measures could create loopholes. DSM in the Area exemplifies this risk: it shares the same geographical jurisdiction as BBNJ but is governed separately.

The Deep Seabed Mining Flashpoint

The Area and its minerals are the common heritage of [hu]mankind (CHM) (Article 136 UNCLOS). Any exploration or exploitation of the Area can only be undertaken under the regulation of the intergovernmental body established for this purpose, the International Seabed Authority (‘ISA’). UNCLOS expressly prohibits any unilateral claim or recognition of mineral rights, outside of the ISA’s regime, applying this prohibition to all States and to all natural and juridical persons (Article 137 UNCLOS). 

Article 137 has garnered scant attention since its drafting in 1982… until now. In April 2025, the President of the USA – one of the few non-UNCLOS States – announced plans to issue DSM permits for the Area under pre-UNCLOS 1980 domestic legislation that does not recognise the ISA or its rules (agreed to by the ISA’s 170 member States). Soon after, a US company “TMC USA” submitted DSM applications under this US law.

These moves create geopolitical tension and raise legal complexities [see: ISA Secretary-General Statement; EJIL:Talk! Blogpost by Lathrop]. One peculiar aspect is how TMC USA’s operations currently rely heavily on nationals and companies from UNCLOS States, despite any such participation being explicitly prohibited by UNCLOS (Articles 137-139 of UNCLOS). Involvement would place those actors (and their home States) in contravention of binding international obligations [see: EJIL:Talk! Blogpost by Fisher and Robb]. Interesting questions arise about the reach of UNCLOS provisions along the DSM value chain. Though untested in case law, the prohibition likely extends beyond direct conduct of DSM. Does it include sub-contractors, technical advisors, financiers, insurers, ports, logistics providers, shipping registries, and downstream purchasers? Clarification through judicial interpretation would be valuable. 

Gaps and the Need for Effective Ocean Governance in ABNJ

Articles 137 and 139 of UNCLOS presuppose domestic implementation (as international law usually binds States and does not directly bind their nationals or legal entities referred to in these provisions). Yet most UNCLOS States lack national laws that translate these obligations into enforceable prohibitions, let alone provide jurisdictional scope or procedural clarity over supply chain involvement. 

These gaps undermine UNCLOS’ integrity and complicate its enforceability. While Article 137 is undeniably actionable against States parties internationally, failure to implement it in national law reduces its deterrent value against private actors and may shift legal accountability towards  States, rather than to the private sector actors directly responsible. 

Weakening  UNCLOS through implementation failure impairs States’ ability to govern ocean resources and protect the environment in ABNJ, core aims of the BBNJ Agreement. The BBNJ legislative process offers a timely opportunity to fix these gaps by incorporating Articles 137-139 into ocean-related legal reforms already underway in many UNCLOS States.

Precedents from National Legislation

There are precedents from which States can draw. Some UNCLOS States have enacted national DSM laws to implement Part XI of UNCLOS, some of which give domestic effect to Articles 137-139.  Most are States sponsoring ISA contracts (Belgium, China, Czech Republic, Germany, Japan, Kiribati, Singapore, Tonga, UK) though not exclusively (e.g. Federated States of Micronesia, New Zealand, Tuvalu) [see: ISA National Legislation Database].

Our research finds at least 12 examples, which range in scope and level of detail, but include:

• Recognition of the Area’s CHM status, and the ISA’s authority.
• Express prohibition on unauthorised exploration or exploitation of the Area.
• Defining ‘unauthorised’ as lacking both ISA and State permission.
• Clarification of actors to whom the prohibition applies (e.g. State bodies, nationals, residents, companies incorporated under the country’s law, vessels registered under the State’s flag).
• Extraterritorial application of the prohibition.
• Clarification of related activities covered by the prohibition (e.g. transport, storage, acquisition, disposal of minerals).
• Criminalisation of violations, with penalties including fines, forfeiture of proceeds of crime, and imprisonment.
• General affirmation of UNCLOS Part XI and the 1994 Agreement, requiring consistency of national legislation and granting national courts jurisdiction to hear related claims.

Additional Drafting Suggestions

Depending on jurisdiction and legislative approach, States may consider fully incorporating similar provisions into their BBNJ Bills or include more general provisions in the Bill, fleshing out detail in secondary legislation or other implementing instruments. At minimum, BBNJ Bills should include a catch-all provision making UNCLOS obligations domestically enforceable.

However, it is further advised that States that have not implemented Part XI provisions should include the Article 137 prohibition and offence in the BBNJ Bill. Doing so promotes UNCLOS compliance, and need not offend the purpose of the Bill, given that the BBNJ Agreement aims to strengthen the comprehensive global regime under UNCLOS and to conserve and sustainably use marine biodiversity beyond national jurisdiction through effective implementation of UNCLOS (Preamble and Article 2 BBNJ Agreement). Moreover, given that the BBNJ Agreement’s scope extends to the Area and expressly affirms the CHM principle (Article 7 BBNJ Agreement), any domestic implementation of its provisions should expressly acknowledge the Area’s CHM status and the core prohibition on appropriation – naturally linking to the necessary domestication of Articles 136-139 of UNCLOS. 

The above existing precedents (drafted between 1981 and 2023) predate today’s concrete threat of unilateral DSM in the Area. The evolving context could warrant additional ideas for legislative measures. States could consider:

• Defining the scope of unauthorised activities to cover downstream, midstream and upstream supply chain activities as well as ancillary actions such as financing, assisting, supporting or facilitating unauthorised activities.
• Criminalising attempts or conspiracies to engage in such activities.
• Defining the scope of subjects of the prohibition, to also include legal persons in the country who exercise control over entities carrying out unauthorised activities, or who carry out substantial business within the State.
• Setting a mens rea threshold e.g. knowledge or wilful blindness.
• Empowering customs and port authorities to deny entry or detain cargo/ vessels linked to unauthorised DSM.
• Mandating domestic agencies and procedures for investigation and prosecution.
• Clarifying the legal status, and handling of seized minerals (or their derivatives or proceeds).
• Ensuring coherence with related laws (e.g. trade, export and import controls, money laundering, investment, maritime regulation, supply chain due diligence, raw material sourcing). 

Strategic Opportunity to Piggyback on BBNJ Implementation

Integrating Articles 137-139 implementation measures into national BBNJ laws may prove to be both legally defensible and strategically advantageous. As noted above, preventing unauthorised DSM in the Area is highly relevant – necessary even – to the mandate of the BBNJ Agreement. The BBNJ Agreement’s core aims of conservation and sustainability could be fatally undermined by environmental harm from unregulated DSM in the Area, outside the ISA’s oversight and environmental rules (Article 145 UNCLOS). As the third UNCLOS implementation agreement, the BBNJ Agreement depends on the integrity and enforceability of UNCLOS itself. A breakdown of UNCLOS Part XI would fracture legal coherence and weaken the BBNJ Agreement’s normative authority, before it has even entered into force.

States could, in principle, adopt standalone domestic legislation, separate from BBNJ legislative processes, to implement Articles 136-139 (and Part XI of UNCLOS more broadly). However, there is no sign States are pursuing this with any urgency,  whilst BBNJ Agreement implementation currently has momentum. Bundling DSM provisions into BBNJ legislation offers administrative and political efficiencies. Lawmaking – developing policy, drafting legislative and explanatory texts, stakeholder consultations, Parliamentary debates – is time and resource-intensive. Whereas adding targeted clauses on unauthorised DSM would require incremental drafting effort and could even avoid delays by pre-empting concerns about this DSM gap that might otherwise delay BBNJ Bill progress. 

Bundling also advances the principle of systemic integration. International law requires treaty obligations to be interpreted in the context of the broader legal system (Article 31 (3)(c) of the VCLT) [see also: Opinion by McLachlan and Fisher]. Aligning BBNJ and UNCLOS Part XI domestically would reinforce the unity of the legal regimes governing the high seas and the Area, and reduce legislative fragmentation or the risk that implementation of one international instrument undermines the other.

A valid counterpoint is that linking DSM to BBNJ could politicise or complicate BBNJ implementation progress. DSM remains divisive, and raising these concerns might be unnecessarily controversial or trigger further political negotiations, stalling progress. More practically, combining BBNJ and DSM measures may be complex if handled by different ministries. Yet these challenges do not negate the ‘elephant in the room’: Part XI obligations have been ratified but remain unimplemented in most States. Strategically framed drafting, supported by targeted explanatory notes and stakeholder engagement, could clarify the legal and policy rationale for bundling. 

Conclusion

The BBNJ Agreement’s ratification provides a rare legislative window to any State implementing its provisions to align domestic law with the full suite of international obligations governing ABNJ, especially the crucial UNCLOS Articles 136-139. Seizing this opportunity would promote legal coherence and political efficiency, while protecting States from treaty non-compliance, and deterring unlawful DSM. The effort required to integrate these provisions into an existing domestic legislative process seems favourable compared with the resources required to develop a new, standalone law to implement Part XI of UNCLOS – or compared to the potential consequences of inaction. A Government that integrates implementation of UNCLOS Articles 136-139 into its BBNJ Bill may also achieve something more than efficiency, or regulatory coherence: it would send a decisive signal at this crucial juncture of zero tolerance to the unlawful annexation of the CHM.