Coastal State jurisdiction and enforcement powers over continental shelves submitted to the CLCS: an analysis of the Rio Grande Rise and the RV Maria S. Merian Episode (2023)

Abstract This article examines whether a coastal State may require the cessation of unauthorised foreign seabed activities in an area submitted to the Commission on the Limits of the Continental Shelf (CLCS) but not yet confirmed as part of its outer continental shelf. The question is examined through the 2023 episode in which the Brazilian Navy ordered the German research vessel RV Maria S. Merian to halt planned seabed coring on the central Rio Grande Rise, a feature included in Brazil’s pending CLCS submission. Using doctrinal analysis of Parts VI, XI and XIII of the United Nations Convention on the Law of the Sea (UNCLOS), relevant case law and recent State practice, the article develops two alternative but convergent arguments. If the Rio Grande Rise forms part of the Area, material coring in a mineral-rich feature would require authorisation from the International Seabed Authority. If it is instead Brazil’s outer continental shelf in formation, Brazil holds a limited protective or conservatory competence over the seabed, subsoil and resource-related data of the submitted area. That competence is not equivalent to full jurisdiction over a finalised shelf, but it suffices to justify proportionate, non-coercive measures against unauthorised interference with the seabed. The study concludes that Brazil’s 2023 cessation order was legally defensible, provided it remained confined to seabed activities and did not interfere with navigation. The finding has direct implications for maritime governance and for policy-making over extended continental shelves.