Maritime Law is the law that governs legal matters related to our oceans, seas and any bodies of open water. It covers everything from the operation of private maritime businesses to the investigation and prosecution of criminal offenses that occur in our oceans.

Whether a case falls within admiralty jurisdiction is usually the first issue considered by admiralty lawyers upon receipt of a case. This is a threshold issue because how it is resolved will determine what law will apply to the case.

A case will fall within admiralty jurisdiction if: (1) it is a federal court case; (2) the issue involves a federal claim; and (3) there is settled federal admiralty law on that issue. If there is no settled federal admiralty law on an issue, state law will apply to the matter.

The jurisdiction of maritime courts is derived from article III of the United States Constitution and is extremely broad, particularly when the scope of the subject matter is ius gentium or the law of nations. As such, it includes all navigable waters, including artificial ones, which by reasonable improvement can be made navigable.

It also covers all claims of injury, damage or death to any person while at sea, on the high seas (the open or unenclosed waters starting at low-water mark), or in any other body of water.

Various international conventions have been adopted to govern the operation of ships, which are enforced by member states through their Port State Control and national courts. These laws differ from country to country, but are generally accepted worldwide.