Did you know that oceans cover approximately 140 million square miles and make up 72% of Earth’s surface? This massive body of water needs a proper system of governance that we now call the law of the sea.
The United Nations Convention on the Law of the Sea (UNCLOS) serves as the foundation of maritime law. It came into force in 1994 and has become the most recognized source of international maritime law. The framework contains 320 articles and nine annexes, with 168 states ratifying it as of June 2019. Most people on Earth live within 200 miles of the sea, and these regulations affect global commerce and human activities in ocean zones.
This piece will help you understand how this legal framework shapes our relationship with oceans. You’ll learn about basic principles, maritime zones, and the essential mechanisms that govern international waters.
Historical Evolution of the Law of the Sea
The rules that govern our oceans today came from centuries of debate, conflict, and cooperation. Ancient Mediterranean civilizations first wrote down maritime laws between 900 and 300 BCE. These laws became the foundation for modern ocean governance. The relationship between nations at sea has always centered on one key question: should oceans be free or controlled?
From Mare Liberum to Modern Maritime Law
Two opposing ideas about ocean governance emerged in the early 17th century. Dutch jurist Hugo Grotius published Mare Liberum (“The Free Sea”) in 1609. He believed oceans were international territory that no single nation could claim. Grotius managed to keep his position that seas couldn’t be owned, couldn’t be controlled by any ruler, and should stay open for everyone.
English jurist John Selden supported the opposite view with Mare Clausum (“The Closed Sea”). He believed nations could own the sea just like they owned land. Their disagreement showed how maritime powers wanted either to protect or grow their influence.
Grotius’s idea of Mare Liberum dominated for more than 300 years. The concept worked well for maritime powers, but challenges started mounting in the 20th century as population grew and technology advanced.
The Truman Proclamation of 1945: A Turning Point
On September 28, 1945, U.S. President Harry S. Truman made a decision that changed maritime law forever. His executive order extended United States control over the seabed and subsoil of the Outer Continental Shelf. The proclamation stated that “the natural resources of the subsoil and sea bed of the continental shelf beneath the high seas but contiguous to the coasts of the United States belong to the United States”.
This new approach was radically different from existing rules, which only gave nations control over a narrow strip of coastal waters. The Truman declaration became international law faster than any other. Legal scholar Sir Hersch Lauterpacht said in 1950 that it became “instant custom” because other nations quickly accepted or copied it.
Other countries soon made similar claims. Argentina claimed its shelf and epicontinental sea in October 1946. Chile and Peru followed in 1947, and Ecuador in 1950 claimed rights over 200-mile zones to protect their fishing. Egypt, Ethiopia, Saudi Arabia, Libya, Venezuela, and several Eastern European countries pushed their territorial seas to 12 miles, far beyond the traditional three-mile limit.
UNCLOS I, II, and III: Progressive Development
The growing number of individual claims called for a unified international system. The United Nations held its first Conference on the Law of the Sea (UNCLOS I) in Geneva, Switzerland in 1958. Four conventions came from this conference:
- Convention on the Territorial Sea and Contiguous Zone
- Convention on the Continental Shelf
- Convention on the High Seas
- Convention on Fishing and Conservation of Living Resources of the High Seas
UNCLOS I made progress but left some key issues unresolved, like how far territorial waters should extend. A second UN Conference (UNCLOS II) in 1960 didn’t lead to any new agreements.
The UN’s third and most detailed Conference on the Law of the Sea ran from 1973 to 1982. More than 160 sovereign states took part in lengthy negotiations. The conference ended with the United Nations Convention on the Law of the Sea on December 10, 1982.
This groundbreaking treaty became known as the “constitution for the oceans.” It created detailed frameworks for territorial waters, sea-lanes, and ocean resources. The treaty introduced new concepts like archipelagic status and exclusive economic zones that stretched 200 nautical miles from shores. UNCLOS became active on November 16, 1994, after 60 nations ratified it, replacing all earlier conventions.
The shift from traditional practices to international law stands as one of humanity’s greatest cooperative achievements. We have a long way to go, but we can build on this progress. Some nations, including the United States, still haven’t ratified the convention. This shows the ongoing struggle between national interests and international governance.
Maritime Zones Under International Law of the Sea
Modern maritime law splits oceans into specific zones. These zones balance the interests of coastal states with international navigation rights. The United Nations Convention on the Law of the Sea (UNCLOS) defines these zones from shorelines to deep ocean.
Territorial Sea (0-12 nm): Sovereign Waters
A nation’s territorial sea extends 12 nautical miles from its baseline, which usually follows the low-water line along the coast. Coastal states have sovereignty over these waters, the airspace above, and everything below. This concept grew from the “cannon shot” rule in the 17th century. Back then, coastal control reached only as far as shore-based cannons could fire—about 3 nautical miles.
Coastal states have almost complete sovereignty in territorial waters, just like on land. Yet one exception remains: foreign vessels can still exercise their right of “innocent passage” through these waters. UNCLOS made the 12-nautical-mile territorial sea official in 1982, after it gained widespread acceptance.
Contiguous Zone (12-24 nm): Limited Enforcement
The contiguous zone sits right next to the territorial sea and reaches 24 nautical miles from the baseline. States can’t claim full sovereignty here but can enforce laws about customs, finances, immigration, and health regulations.
Law enforcement needs brought the contiguous zone into existence. U.S. legislation from 1799 let authorities stop foreign vessels within 12 nautical miles of the coast. This zone started as “customs waters” and gives states practical power without full sovereignty. It stops criminals from escaping by simply sailing past territorial waters.
Exclusive Economic Zone (24-200 nm): Resource Rights
The EEZ stands as one of UNCLOS’s biggest achievements, reaching 200 nautical miles from the baseline. Coastal states in this zone have:
- Sovereign rights to explore, exploit, conserve, and manage all natural resources in the water, seabed, and subsoil
- Exclusive rights to generate energy from water, currents, and winds
- Jurisdiction over artificial islands, scientific research, and environmental protection
Other nations keep important freedoms in the EEZ, such as navigation, overflight, and laying submarine cables and pipelines. Declared EEZs now cover about 42% of the world’s oceans.
Continental Shelf: Seabed Jurisdiction
The continental shelf includes the seabed and subsoil beyond the territorial sea, following the natural extension of land territory. Coastal states have exclusive rights to explore and use natural resources on or under the seabed.
Every nation’s continental shelf automatically extends to at least 200 nautical miles from the baseline. Nations can claim jurisdiction up to 350 nautical miles from shore or 100 nautical miles beyond the 2,500-meter depth contour if their geographical continental margin goes further. This depends on specific technical criteria.
Nations must submit scientific evidence to the Commission on the Limits of the Continental Shelf to establish these extended claims. Approved boundaries become “final and binding”.
High Seas: Freedom and Governance Beyond National Control
The high seas cover all ocean areas beyond national jurisdiction—mostly past the 200-nautical-mile EEZ limit. This makes up about 64% of the world’s oceans and nearly half of Earth’s surface.
All states enjoy traditional freedoms on the high seas, including navigation, overflight, fishing, scientific research, and laying submarine cables. Different regional and sectoral organizations have managed these areas separately.
The “High Seas Treaty” (officially the Biodiversity Beyond National Jurisdiction treaty) addresses this challenge. It creates new ways to establish marine protected areas, control access to marine genetic resources, and set standards for environmental impact assessments.
This groundbreaking agreement came together in 2023. It provides the first complete governance framework for international waters in almost two decades and sets the stage to protect at least 30% of ocean areas by 2030.
Navigation Rights and Passage Regimes
Maritime navigation rights in different zones are the life-blood of international maritime law. The United Nations Convention on the Law of the Sea (UNCLOS) sets up four different passage regimes. These regimes create a balance between navigational freedoms and coastal state sovereignty.
Innocent Passage Through Territorial Waters
Ships traversing territorial seas have innocent passage rights, which represent the most limited navigation right. A passage becomes “innocent” only when it “does not harm the peace, good order or security of the coastal State” and follows UNCLOS and international law guidelines.
This right comes with strict limits. To name just one example, submarines must surface and display their flag. The passage becomes non-innocent when vessels take part in any of twelve prohibited activities:
- Weapons exercises or threats against coastal state sovereignty
- Intelligence collection or propaganda activities
- Launch or landing of aircraft or military devices
- Fishing, pollution, or unauthorized research
Coastal states can temporarily suspend innocent passage in specific areas to protect their security. Such suspension requires public announcement and must treat all vessels equally.
Transit Passage Through International Straits
Transit passage rules apply to straits that connect one part of the high seas or exclusive economic zone (EEZ) to another. Bordering states cannot suspend transit passage, unlike innocent passage.
Ships get substantially broader rights here, including:
- Continuous and expeditious transit in “normal mode” of operation
- Freedom for submarines to transit submerged
- Overflight rights for aircraft
This creates a balance between maritime powers who want unimpeded navigation and coastal states concerned about security. Ships and aircraft must move without delay, avoid threats or force, and follow international safety and pollution rules.
Archipelagic Sea Lanes Passage
UNCLOS introduced archipelagic sea lanes passage as a new concept. This addresses unique geographic needs of archipelagic states like Indonesia and the Philippines. Foreign ships and aircraft can travel through designated sea lanes that cross archipelagic waters.
Article 53 of UNCLOS lets archipelagic states create sea lanes “suitable for the continuous and expeditious passage of foreign ships and aircraft”. These lanes must cover all normal international navigation routes. Continuous axis lines define these lanes from entry to exit points.
Ships cannot deviate more than 25 nautical miles from these axis lines during passage. Ships can use routes normally used for international navigation if an archipelagic state hasn’t designated sea lanes.
Freedom of Navigation in the EEZ and High Seas
UNCLOS grants more freedoms beyond territorial waters. All states can enjoy navigation, overflight, and submarine cable and pipeline laying rights in the EEZ. These match high seas freedoms but must respect coastal state rights.
Navigation freedoms reach their peak on the high seas. Article 87 of UNCLOS states that “the high seas are open to all States, whether coastal or land-locked”. Flag states have exclusive jurisdiction over their ships on high seas. Warships and government vessels get complete immunity from other states’ jurisdiction.
Navigation freedom, though fundamental to maritime law, has its limits. Warships can check foreign vessels they suspect of piracy, slave trade, unauthorized broadcasting, or sailing without nationality.
Resource Management Under Law of the Seas
Ocean resources need careful management under international maritime law. The United Nations Convention on the Law of the Sea (UNCLOS) provides detailed frameworks that govern how nations can learn about, use, and conserve marine resources of all types.
Fisheries Regulation and Conservation
Fisheries are vital living resources that need balanced management approaches under UNCLOS. Coastal states have complete authority over fishing activities within territorial seas and archipelagic waters. The exclusive economic zone (EEZ) gives coastal states “sovereign rights for exploring, exploiting, conserving, and managing natural resources” as you move further offshore.
Coastal states must set up conservation measures to prevent over-exploitation according to Article 61. This happens through catch limits based on scientific evidence. Article 62 requires states to promote “optimal utilization” of these resources. When a coastal state can’t harvest the entire allowable catch, it must let other states access the surplus.
Fishing freedom on high seas comes with responsibilities beyond national jurisdiction. Every state can fish on high seas but must also protect living resources, as outlined in Articles 116-119. Nations must work together to manage shared stocks, especially highly migratory species. The 1995 UN Fish Stocks Agreement strengthened this framework.
Mineral and Energy Resource Exploitation
Coastal states have exclusive rights to explore and use non-living resources within their continental shelves and EEZs. These rights include oil, natural gas, and mineral deposits found in the water, seabed, and subsoil. States also have exclusive rights to use energy from waves, currents, and wind within their EEZ.
The continental shelf regime lets coastal nations exercise sovereign rights over seabed resources, whatever the formal occupation or express proclamation. This principle came from the 1945 Truman Proclamation, which claimed U.S. jurisdiction over continental shelf resources—other nations copied this claim quickly.
Deep Seabed Mining in the Area
The deep seabed beyond national jurisdiction—officially called “the Area”—follows completely different principles. Article 136 states that the Area and its resources are the “common heritage of mankind“. This basic principle means no state can claim or control any part of the Area or its resources.
UNCLOS created the International Seabed Authority (ISA) in Jamaica to regulate activities in the Area. The ISA develops the “Mining Code”—rules that govern prospecting, exploration, and use of marine minerals. The ISA has signed 15-year contracts with 21 contractors to explore polymetallic nodules, polymetallic sulfides, and cobalt-rich ferromanganese crusts.
Exploitation regulations are still being developed. A newer study found “more than 30 major outstanding issues” including environmental impact monitoring and assessment. These regulations want to balance economic development with “rigorous environmental protection”. Several nations like Chile, Costa Rica, France, and Germany have suggested taking a cautious approach before commercial mining starts.
Marine Genetic Resources: Emerging Frontiers
Marine genetic resources (MGRs)—”any material of marine plant, animal, microbial or other origin containing functional units of heredity of actual or potential value”—are opening new frontiers in oceanic resource management.
The 2023 “Biodiversity Beyond National Jurisdiction” (BBNJ) Agreement tackled MGRs in areas beyond national jurisdiction. This agreement sets up frameworks for notification requirements and benefit-sharing mechanisms. Both monetary and non-monetary benefits must be shared “fairly and equitably” through special funding mechanisms.
Non-monetary benefits cover access to samples, scientific data, technology transfer, and capacity-building opportunities. Monetary benefits from commercialization will come through “decoupled payments” from developed states initially, with reviews every two years.
UNCLOS and its implementing agreements form a growing framework that balances sovereign resource rights with conservation duties to preserve ocean resources for future generations.
Enforcement Mechanisms and Dispute Resolution
Maritime law enforcement needs specialized international bodies that can resolve disputes between nations. The United Nations Convention on the Law of the Sea (UNCLOS) created a complete dispute resolution system. This system balances national sovereignty with international cooperation.
International Tribunal for the Law of the Sea (ITLOS)
Hamburg, Germany hosts the International Tribunal for the Law of the Sea, an independent judicial body UNCLOS created to settle disputes about the Convention’s interpretation and use. The tribunal has 21 judges that States Parties elect. These judges represent the “principal legal systems of the world” and maintain “equitable geographical distribution”.
ITLOS can handle:
- Disputes submitted under UNCLOS
- Cases explicitly provided for in other agreements
- Prompt release of vessels and crews
- Provisional measures pending arbitral tribunal formation
Article 287 lets ITLOS share jurisdiction with other forums like the International Court of Justice and arbitral tribunals. The Tribunal has handled 25 cases since its creation, from vessel detention to maritime boundary issues.
Commission on the Limits of the Continental Shelf
The Commission on the Limits of the Continental Shelf (CLCS) helps implement UNCLOS rules about continental shelf boundaries beyond 200 nautical miles. Coastal states submit scientific data that the Commission reviews. Article 76(8) states that the Commission’s recommendations become “final and binding” once accepted.
The CLCS doesn’t settle boundary disputes between states. Instead, it focuses on proving scientific claims about continental shelf extents. The Commission has received 61 submissions. They’ve adopted recommendations for 18, are thinking over 6, and 37 await review.
International Seabed Authority Functions
Kingston, Jamaica houses the International Seabed Authority (ISA), which UNCLOS and the 1994 Implementation Agreement established. ISA regulates mineral activities in “the Area” – seabed beyond national jurisdiction. The Council leads ISA’s operations by creating specific policies and regulations.
ISA must balance two goals: authorizing seabed development and protecting marine ecosystems. They’ve approved 28 exploration contracts that cover more than 1.3 million square kilometers of ocean floor.
Arbitration Procedures Under UNCLOS Annex VII
States use Annex VII arbitration when they haven’t accepted the same procedure or declared preferred forums. Each arbitral tribunal has five members. Both parties appoint one member each, and they jointly select the other three.
Article 9 states that proceedings continue even if a party doesn’t show up. The South China Sea case proved this when China refused to participate. Tribunals give final, binding awards that parties must implement.
The Permanent Court of Arbitration has managed 14 UNCLOS Annex VII arbitrations since 1994. These cases covered everything from maritime boundaries to vessel detention.
Contemporary Challenges to Maritime Law
Maritime law faces new challenges that test the strength of frameworks that are centuries old. The changing ocean environment demands adaptation from international legal systems to handle new threats.
Climate Change and Rising Sea Levels
Coastal nations, particularly Small Island Developing States, face existential threats from rising seas. The Intergovernmental Panel on Climate Change has confirmed that global mean sea level has risen faster since 1900 than at any point in the last 3,000 years. Low-lying coastal zones house about 680 million people now, and this number could exceed 1 billion by 2050.
These shifts create tough legal questions about maritime boundaries and sovereignty. The Pacific Islands Forum took action with its 2021 Declaration on Preserving Maritime Zones. The declaration states that maritime zones should stay fixed despite changes from rising seas. Legal experts now agree that states should keep their baselines and outer limits of maritime zones, whatever the territorial changes.
Piracy and Maritime Security Threats
Ships worldwide still face threats from pirates. UNCLOS Article 101 defines piracy as illegal violent acts committed for private gain against ships on the high seas. These crimes disrupt global shipping, cause financial damage, and sometimes lead to loss of life.
Countries working together have found ways to curb piracy. The Regional Cooperation Agreement on Combating Piracy in Asia (RECAAP) and the Djibouti Code of Conduct for the Western Indian Ocean region stand out as success stories.
Illegal, Unreported, and Unregulated Fishing
IUU fishing damages ocean ecosystems and sustainable fisheries worldwide. This includes unlicensed fishing, catch misreporting, and violations in protected areas. Maritime CO2 emissions grew by 2.1% yearly between 2011 and 2019.
International cooperation through regional fishery bodies, port state measures, and market tools helps fight IUU fishing. Developing countries that rely on fishing for food and income suffer the most. West Africa’s actual catches exceed reported numbers by 40%.
Marine Pollution and Environmental Protection
Oil spills, plastic waste, and greenhouse gasses all contribute to marine pollution. The International Tribunal for the Law of the Sea made a groundbreaking decision when it classified greenhouse gas emissions as marine pollution. This ruling made it clear that states must protect marine environments from climate change.
UNCLOS Article 194 requires states to control all types of marine pollution. These rules protect rare ecosystems and endangered species’ habitats.
Conclusion
Maritime law proves international cooperation works, as it progressed from ancient Mediterranean codes into today’s complete framework under UNCLOS. Nations now share a common understanding of ocean governance through defined maritime zones, centuries-old navigation rights, and structured resource management systems.
The law of the sea creates perfect balance between competing interests. Coastal states’ sovereignty within territorial waters coexists with navigation freedom. Resource management frameworks safeguard national interests and global commons together. ITLOS and arbitration procedures serve as tools that help maintain this delicate balance.
Most important challenges continue to surface. Climate change affects long-standing maritime boundaries. Piracy and IUU fishing threaten both security and eco-friendly practices. The international community needs adaptive responses to these emerging problems.
Maritime law’s future relies on ongoing cooperation and progress. Nations must unite to handle rising sea levels, curb marine pollution, and ensure eco-friendly resource management. Their actions will shape our oceans’ health and determine the stability of international governance systems.
