Brazilian jurisdictional waters (, AJB) are the riverine and oceanic spaces over which Brazil exerts some degree of jurisdiction over activities, persons, installations and natural resources. They comprise internal waters, the territorial sea and exclusive economic zone (EEZ), to a distance of from baselines along the coast, as well as waters overlying the extended continental shelf, where Brazilian claims of jurisdiction are controversial, as the water column over this stretch of seabed is part of the high seas., , . The continental shelf of Brazil is under a different legal regime from its overlying waters. The Brazilian Navy covers both the shelf and the waters in its less formal concept of a "Blue Amazon".

The AJB's total claimed area stands at 5,669,852.41 km² (equivalent to 67% of land territory), of which 2,094,656.59 km² are above the extended shelf. These maritime zones are based on the United Nations Convention on the Law of the Sea (UNCLOS). From 1970 until it came into effect in 1994, Brazil had claimed a territorial sea as far as 200 nautical miles from the coast, instead of the present 12, but retains rights over natural resources in this area through its EEZ. Its coastline is the longest in the South Atlantic Ocean, but only three archipelagos contribute to its EEZ: Fernando de Noronha, Trindade and Martim Vaz and Saint Peter and Saint Paul.

Brazil's marine ecosystem is hydrographically and topographically complex and exhibits high rates of endemism and an economic potential in biotechnology. The two prevailing ocean currents, Brazil and North Brazil, have warm, nutrient-poor waters sustaining relatively low biomasses for each species, with a correspondingly limited fishing potential. In winter, cold waters of the Falkland Current may reach as far as the 24th parallel south and cold fronts and extratropical cyclones bring rough seas. The wind, waves, tides and thermal and osmotic gradients offer untouched potentials for renewable energy generation. 26.4% of the EEZ was under protected areas in 2021, mostly around the remote archipelagos of Saint Peter and Saint Paul and Trindade and Martin Vaz. Both are only populated by researchers and military personnel, which is one of the reasons for the government's marine science programs.

Most of the country's population lives near the coast and most of its international trade is conducted through the sea, but local shipbuilding and the national merchant marine have little presence in this trade. Coastal shipping answers a modest share of internal trade and mostly covers the oil and natural gas sector. There is no official measurement of the Brazilian maritime economy; 2015 estimates placed it at 2.67% of the gross domestic product directly tied to the sea, mostly in the tourism-dominated service sector. Coast guard duties in jurisdictional waters are assigned to the Navy.

Definition International law

Brazilian regulation on maritime spaces follows UNCLOS, a codification of international maritime law which came into force in 1994. This Convention, ratified by 168 states as of 2022, unifies centuries of rulemaking on interstate disputes over control of the seas. It organizes the sea off the coast of sovereign states in multiple zones: the territorial sea, contiguous zone, exclusive economic zone and continental shelf. Distances are measured in nautical miles from baselines along the coast. There are two kinds of baseline: normal lines, which follow the low-water line as plotted on official charts, or straight lines where the coast is too jagged or island-strewn.

The territorial sea extends up to from baselines and grants coastal states sovereignty over the airspace, water column, seabed and subsoil. Each of these spaces is treated separately in the other maritime zones. In the contiguous zone, at 12 to 24 miles from baselines, a coastal state does not have full sovereignty, but may take measures to prevent or repress unlawful activities in its territory or territorial sea. The contiguous zone is part of the EEZ, which has a width of 188 miles, from the limit of the territorial sea until a distance of from baselines. This area gives a coastal state jurisdiction over the exploitation, conservation and management of its waters, seabed and subsoil. The high seas begin at the EEZ's outer limit.

The continental shelf as defined in international law is distinct from the geological continental shelf and consists in an area of seabed and its subsoil, excluding the overlying water column, over which a coastal state has sovereign rights over its natural resources. It extends "to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines", as defined in the UNCLOS. If a coastal state's continental margin extends beyond 200 nmi, it may propose an extended continental shelf to the Commission on the Limits of the Continental Shelf (CLCS), an international organ created by the UNCLOS.

Brazilian law

The term "Brazilian jurisdictional waters" (, AJB) exists in legislation since 1941 at the earliest, although it was less common than "Brazilian waters", "waters of the territorial sea" or "territorial waters".Decree-Law n. 2,986, January 27 1941. . The territorial sea has had a legal definition since 1850, an exclusive fishing regime since 1938, a continental shelf since 1950, and a contiguous zone since 1966.Decree-Law n. 44, November 18 1966. . An extended continental shelf was first proposed in 2004 and the country has yet to reach a full understanding with the CLCS to make its claims final and binding.

Law no. 8,617 of January 4, 1993 defined Brazil's maritime zones according to the UNCLOS definitions, and Decree no. 1,530 of June 22, 1995 reproduced the convention's text, making it enforceable within the country. When ratifying the convention, Brazil also announced any foreign military operations within its EEZ must be notified in advance. The concept of AJB was becoming commonplace in legislation since a 1987 law on the prohibition of whaling within the AJB. Other legislative acts used expressions such as "waters under Brazilian jurisdiction", "waters under national jurisdiction" and "Brazilian jurisdictional marine waters", but the Navy took a liking to AJB. This term was used for many years without an explicit definition until the Maritime Authority's Norms for the Operation of Foreign Waters in Brazilian Jurisdictional Waters ( – NORMAM-04/2001 (Ordinance 61/, September 22, 2001):

The Navy has the jurisdiction to complete and expound on the gaps in national maritime legislation, and therefore, definitions given in its norms prevail over others. Matching definitions have been given in other editions of the NORMAM and in the 2014 Navy Basic Doctrine, which further established that the AJB cannot be considered part of the high seas. Presidential decrees and the National Defense White Paper, which was ratified by Congress in 2018, have accepted the Navy's definition.

Brazilian law regulates maritime traffic, environmental conservation, natural resource exploitation and scientific research in the AJB. Internal waters and the territorial sea are its only components which are part of Brazil's territory, where the state exerts full sovereignty. The EEZ and continental shelf merely offer sovereign rights over natural resources. Therefore the expression "Brazilian maritime territory", which some authors used for the totality of Brazilian maritime zones, is misleading.

Waters overlying the extended continental shelf

Some legal scholars have criticized the Brazilian state's claim of jurisdiction over the water column overlying its extended continental shelf. Beyond 200 nmi, the water column is part of the high seas, even when its underlying seabed belongs to a state's continental shelf. At the International Journal of Marine and Coastal Law, Alexandre Pereira Silva summarized in 2020 that the concept of AJB is incompatible with the UNCLOS and infringes on the freedom of the high seas. Tiago V. Zanella, an author on maritime law, does not dismiss the concept's "enormous strategic importance" for the country, but considers that to speak of jurisdictional rights over this area is to perform an "undue appropriation of a zone that is 'open to all states'".

In the hypothetical case of a foreign whaling vessel in the waters overlying the extended continental shelf, over 200 nmi from coastal baselines, Brazilian law would require the Navy to impede this vessel's illegal activities in the AJB. The vessel's owners could resort to an international court, such as the International Court of Justice or the International Tribunal for the Law of the Sea, which would rule in their favor. As a party to the UNCLOS, Brazil would have to comply with this ruling.

Naval officer Alexander Neves de Assumpção, in his thesis for the Naval War College, concedes there is a risk of naval commanders being led to infringe on international treaties ratified by Brazil. Nonetheless, he contended that "the concept of AJB need not be changed", as it is already moderated in legislation by the expressions "jurisdiction, to some degree", "for the purposes of control and oversight" and "within the limits of national and international law". To oversee exploitation of the seafloor, Brazil would still have a limited jurisdiction, not to be conflated with sovereignty, over its overlying waters, even when they lie in the high seas. No country has contested Brazil's definition, and Argentina and Chile have likewise claimed jurisdictions beyond what was given in the UNCLOS. What remained to be done was to draft norms clarifying which kinds of oversight are allowed.

Blue Amazon

To encompass all maritime spaces under Brazilian jurisdiction, in 2004 the Navy publicized the concept of a "Blue Amazon" (), which, as mentioned by admiral Júlio Soares de Moura Neto, Commander of the Navy in 2013, is a synonym for jurisdictional waters. The formal definition is "the region which comprises the surface of the sea, waters overlying the seabed, seabed and subsoil within the atlantic expanse which projects from the coast until the outer limit of the Brazilian continental shelf". The Blue Amazon is not a legal term. It is used in the Navy's external and internal communication, The idea of a Blue Amazon. and by scientific, environmental and other civilian sectors.

The term was coined to draw the public's attention to this area by comparison with the "Green" Amazon's vastness and abundance of natural resources. It is understood in multiple facets, that is, areas of interest to the state: sovereignty and national defense via political-strategic influence in the South Atlantic Ocean, economic prosperity, scientific and technological innovation and environmental conservation, with an emphasis on the first. The Navy has undertaken a national campaign to publicize the concept, seeking popular support to its maritime strategy, the expansion of maritime limits and military re-equipment. More broadly, it promotes the public's "maritime mentality", seeking to regain what its proponents see as an "oceanic destiny" neglected by public consciousness.

Delimitation