There are two basic bodies of law that apply to the seas. The first is known as the Law of the Sea and addresses issues of jurisdiction and navigation over the world's oceans, as well as relationships between nations regarding the bodies of water found throughout the world. The second is International Maritime Law, or Admiralty Law, which covers things such as private commerce, the transportation of goods and passengers, and legal issues that arise such as injuries to sailors or passengers on the sea. As with most areas of international law, international maritime law is a complex web of individual legislation enacted in sovereign states and international or multi-national treaties.
Although individual jurisdictions may enact legislation that applies to international maritime law, there are also a number of international or multi-national treaties that have been signed by various nations of the world in an attempt to apply uniform rules to those who frequent the world's oceans and waterways. As a result, there are a few common "rules" or legal concepts that are almost uniformly accepted and applied. The areas wherein the law is fairly uniform include treatment of sailors, liens, injuries, and salvage.
Dating as far back as we have accurate records regarding admiralty law, shipowners have been required to care for sailors who are injured while at sea. Known as the doctrine of "maintenance and cure," it requires a shipowner to care for an injured sailor until he or she reaches maximum medical cure. Although the precise definition may vary by jurisdiction, this often requires a shipowner to provide extensive medical care and monetary support while the sailor is injured.
Liens for provisions, gas, maintenance, or other goods or services required to operate a ship are also something that most jurisdictions agree upon. Much like a mechanic's lien or contractor's lien on dry land, a lien may be placed on a ship for goods or services supplied to the shipowner. Injures to passengers at sea are typically treated in the same manner as they would be on dry land. A passenger may be entitled to compensation for his or her injuries if he or she can prove negligence on the part of the shipowner.
Salvage laws have also been around for centuries. Vast treasures have been discovered at sea sometimes years, decades, or even centuries after a ship sank. International maritime law must address who has the right to ownership of anything found at sea. As a rule, admiralty law gives the finder of salvage a right to a salvage award, not rights to ownership of the property itself. The value of the award will be based on the value of the salvage and the risk taken to retrieve the salvage in the absence of a prior contract.
Travel by sea was basically the first form of mass transit. Ancient sailors were responsible for discovering new lands for their homeland and opening the door to new civilizations. By the 1800s, travel by sea was regularly used to transport goods around the world as well as passengers. As a result, international maritime law actually has a rather long history. For example, both John Adams and Alexander Hamilton, well-known figures in American history, were admiralty lawyers prior to the American Revolution.