Wikipedia
In admiralty law, a maritime lien is a privileged claim upon sea-connected property, such as a ship, for services rendered to, or the injuries caused by that property. In common law, a lien is the right of the creditor to retain the properties of his debtor until the debt is paid.
It is a proprietary lien where interest is about the property. It should be understood that “res” may be the vessel (including its appurtenances and equipment), the cargo, the freight or even the proceeds of sale. The rights include jus in re (right on the property) and ''jus in rem ''(right against the property). The doctrine of maritime lien is that a ship will be treated as a wrongdoer, not the owner, that the loss, damage or harm is caused by the maritime property, itself, and it has to make good for the loss. The attachment of maritime lien will start when the cause of action arises and will not be eliminated even by change of ownership in a good faith purchase.
Two significant differences between maritime liens, which only exist in admiralty law, and the right to keep that exist in general civil law are (1) that in general civil law, "Prior in time is prior in right", i.e., the rights of the lienholder with the earliest lien are superior to those of later lienholders, whereas in maritime law the rights of the most recent lienholder are superior, and (2) all maritime liens are superior to all non-maritime liens. For instance, in the United States, a federal tax lien, which is a non-maritime lien, is subordinate to every lien for supplies, fuel, repairs, etc., which are all maritime liens.
Normally, a maritime lien relates to the different marine transactions in the admiralty jurisdiction and creates the maritime claims. It will be created by the statute such as the Ship Mortgage Act.