Many people assume that “international waters” are lawless, a place where no country’s rules apply. In reality, international waters are governed by a complex framework of international treaties, maritime conventions, and domestic laws that determine jurisdiction, liability, and enforcement authority. Understanding where international waters begin and what laws apply there is essential for seafarers, cruise passengers, offshore workers, and maritime employers alike.
International waters, often referred to as the “high seas,” are defined under the United Nations Convention on the Law of the Sea as waters beyond any nation’s territorial sovereignty. However, the absence of territorial control does not mean the absence of law. Instead, jurisdiction typically follows the vessel, the individuals involved, and the nature of the incident.
Under the United Nations Convention on the Law of the Sea (UNCLOS), coastal nations exercise sovereignty over territorial seas extending up to 12 nautical miles from their coastline. Beyond that boundary lie international waters, legally known as the “high seas.” Maritime zones are generally divided as follows:
The territorial sea extends from a nation’s coastline out to 12 nautical miles and is subject to the full sovereign authority of the coastal state, meaning its domestic laws generally apply to vessels, individuals, and activities within this zone.
The contiguous zone extends from 12 to 24 nautical miles offshore and grants the coastal state limited enforcement authority to prevent or address violations of customs, fiscal, immigration, and sanitary laws that may affect its territory or territorial sea.
The Exclusive Economic Zone extends up to 200 nautical miles from the coastline and grants the coastal state sovereign rights to explore, exploit, conserve, and manage natural resources, but it does not provide full territorial sovereignty over navigation or foreign vessels. Under Article 76 of the United Nations Convention on the Law of the Sea, a coastal state may extend its continental shelf beyond 200 nautical miles, in some cases up to 350 nautical miles, if it can demonstrate that the seabed is a natural prolongation of its land territory. This extension applies only to seabed and subsoil resources and does not convert those waters into territorial seas.
The high seas begin beyond 200 nautical miles from a nation’s coastline and are not subject to the sovereignty of any single state; however, they remain governed by international law and are typically regulated through flag state jurisdiction and international maritime conventions.
The National Oceanic and Atmospheric Administration (NOAA) provides more detailed explanations of U.S. maritime zones and offshore jurisdiction.
International waters begin beyond 12 nautical miles from a nation’s coastline. However, jurisdictional authority does not end at that boundary. For example:
The United States Coast Guard enforces federal maritime law and safety regulations, including certain offshore activities beyond territorial waters.
Jurisdiction on the high seas typically follows established principles of maritime law. The primary categories include:
Under the principle of flag state jurisdiction, a vessel is governed by the laws of the country in which it is registered, meaning that the flag state retains primary legal authority over the vessel and those aboard it, even when operating in international waters, consistent with the framework established by UNCLOS.
Port state jurisdiction allows a country to enforce its laws and regulatory standards once a vessel voluntarily enters its ports, including the authority to investigate violations, inspect compliance with safety and environmental regulations, and, where appropriate, detain or sanction the vessel.
Universal jurisdiction permits any nation to prosecute certain serious offenses recognized under international law, such as piracy, regardless of where the crime occurred or the nationality of the individuals involved, reflecting the global interest in suppressing conduct that threatens maritime security.
Nationality jurisdiction enables a country to prosecute its citizens for certain criminal or regulatory violations committed abroad, including conduct that occurs on the high seas, provided the relevant domestic statutes extend extraterritorial application.
The International Maritime Organization oversees global maritime safety and regulatory standards, including compliance frameworks affecting vessels worldwide.
International waters are regulated through a combination of international conventions and domestic maritime law. Key governing frameworks include:
The United Nations Convention on the Law of the Sea establishes the foundational legal framework governing maritime zones, navigational rights, flag state responsibilities, and dispute resolution on the high seas.
The Safety of Life at Sea Convention sets minimum international safety standards for the construction, equipment, and operation of vessels in order to promote maritime safety and protect life at sea.
The International Convention for the Prevention of Pollution from Ships, commonly known as MARPOL, regulates the discharge of pollutants into the marine environment and establishes international standards designed to prevent environmental damage caused by vessels.
The Maritime Labour Convention sets global standards governing the working and living conditions of seafarers, including requirements related to wages, hours, accommodations, medical care, and repatriation
In addition to international treaties, domestic admiralty law may apply depending on the vessel’s registration and the individuals involved, and in the United States maritime claims frequently fall within federal admiralty jurisdiction pursuant to Article III of the U.S. Constitution and Title 28 of the U.S. Code.
When an injury occurs beyond territorial waters, determining applicable law becomes more complex but not impossible. Jurisdiction often depends on:
For seamen and maritime workers, federal protections may apply under the Jones Act. The Jones Act allows qualifying maritime employees to pursue negligence claims against their employers, even when injuries occur outside U.S. territorial waters.
Cruise passengers may also have claims governed by federal maritime law and ticket contract provisions, which often designate venue and applicable law. Offshore oil and gas workers may fall under distinct statutory schemes depending on platform location and employment classification.
The Supreme Court of the United States has repeatedly affirmed that maritime law follows vessels and seafarers beyond territorial boundaries.
International waters are not lawless. Criminal acts at sea are typically prosecuted under one of the following authorities:
The U.S. Department of Justice regularly prosecutes maritime crimes, including drug trafficking, assault, environmental violations, and piracy occurring on the high seas. Piracy is subject to universal jurisdiction under international law, meaning any nation may prosecute offenders.
Territorial Waters – Full sovereignty; domestic law applies directly
Exclusive Economic Zone – Economic control; limited enforcement authority
International Waters – No territorial sovereignty; governed by international law and flag state authority
Although sovereignty ends at 12 nautical miles, legal responsibility does not. Maritime employers, vessel operators, and crew members remain subject to binding legal obligations under international conventions and domestic maritime statutes.
Jurisdiction determines:
Admiralty jurisdiction can significantly affect compensation, evidentiary standards, and procedural timelines. Determining proper jurisdiction requires careful legal analysis of vessel registration, employment classification, contractual provisions, and the specific circumstances of the incident.
Understanding the legal framework governing international waters is essential for maritime workers, passengers, and vessel operators. While no nation owns the high seas, conduct on the high seas is regulated by well-established international law principles and domestic maritime statutes.