A more thorough explanation:

General maritime law refers to the body of legal precedents and doctrines that have been developed through caselaw in maritime and admiralty litigation in the United States. It is a branch of federal common law and is different from statutory law.

For example, if a shipowner is sued for negligence in a maritime accident, the general maritime law would be used to determine the liability of the shipowner. The general maritime law is characterized by the expansive and dominant role played by federal courts in fashioning and applying its precepts to new situations.

Large areas of maritime tort law have not been touched by legislation, and these are left to the federal courts to define and fill. In areas preempted by legislation, federal courts may not establish principles in derogation of the congressional mandate. However, in the framework of admiralty jurisdiction, federal courts may still play an active role in interpreting statutes, filling gaps, and coordinating legislation with the general maritime law.

Overall, the general maritime law is an important aspect of the legal system that helps to regulate maritime and admiralty cases in the United States.