Home port, also “homeport,” is the port in which a vessel is registered or permanently based. For merchant vessels, it is the port from which it operates. A ship’s port of registry and the flag under which it sails have legal significance for tax purposes and the application of international maritime law.
A longstanding rule of international maritime law is that a ship engaged in foreign commerce or trade is subject to property taxes only in its home port. This doctrine was incorporated in the Foreign Commerce Clause of the US Constitution. It applies to both foreign trade and commerce between the states from ports within the US.
Some commercial vessels sail under a “flag of convenience.” Under maritime law, the legal country of jurisdiction for an ocean going vessel is the one under which flag it sails. Some countries have an “open registry” policy by which a foreign vessel can register under the country’s flag for an annual fee.
Open registry has economic and legal advantages. It allows vessel owners to select employees from an international pool. It usually avoids the higher labor costs and taxes that come with sailing under the flag of the vessel’s home country, where labor laws may be more strictly enforced or taxes higher. US merchants flag a high number of their ships through registry in Panama. It is estimated that about half the commercial vessels in the world sail under flags of convenience.
Ships traveling under flags of convenience are given scrutiny by maritime law enforcement agencies. Open registry allows for an anonymity of actual home port that makes it attractive to criminal enterprises. These include drug smuggling, human trafficking, and illegal fishing practices.
The laws of a country’s home port also have relevance for ships in distress or in need of assistance. A ship in distress is one at risk of sinking or harm to crewmembers. A ship in need of assistance is one that is damaged or otherwise in need of a safe harbor.
Modern ships pose greater environmental dangers to ports than ships of the past, particularly in cases of potentially massive oil spills from a damaged or disabled vessel. The dangers of the harm to the port and the surrounding environment must be weighed against the loss of property and the safety of the ship’s crew. There are reported cases of ships sinking after being refused port entry. International maritime lawyers still debate the rules that should apply in deciding when to refuse a ship port entry.