Revisiting the “Responsibility to Ensure”: Two-Line Standards of the Sponsoring State’s National Legislation on Deep Seabed Mining

The deep seabed mining regime is composed of international legislation and domestic counterparts. International legislation emanates from the International Seabed Authority (ISA) under the mandate of UNCLOS, which is currently in the accelerated process of being drafted for exploitation activities to meet a deadline of July 2023. In contrast, the development of domestic law in ISA Member States has been relatively slow, and this risks failure to fulfill their obligation of “responsibility to ensure” concluded in the advisory opinion in 2011. This possible failure is partly due to States’ different understanding of their obligation to impose more stringent environmental conditions on contractors in their domestic laws than those specified in the Mining Code adopted by ISA. This paper argues that Annex III, article 21(3) of the UNCLOS requires States to adopt a two-tier approach in their national legislation—minimal and optimal levels. The minimal level requires a sponsoring State to comply with the Mining Code’s fundamental requirements while reaching the optimal level means that the sponsoring State tries its best to establish more stringent standards than the Mining Code. Adopting more stringent requirements may be realized by adopting higher or stricter standards or inserting more details in the national legislation. Moreover, all ISA Member States are, including developing States, obliged to meet the minimum line and encouraged to move towards the optimal one