It is inchoate from the moment the claim or privileges attaches, and when carried into effect by legal process by a proceeding in rem, relates back to a period when it attaches” (cited Mandaraka-Sheppard 22). On the other hand, an in rem action, as opposed to an action in personam, is one that attaches on property rather than on a person. In the maritime context, it attaches on the ship or on the cargo rather than on the ship-owner or the cargo owner. Thus, once a writ is issued by the court in an action in rem, a warrant for the arrest of the ship or cargo, rather than on the ship-owner or the cargo owner, can be applied next to secure the claim even before judgment. Lord Justice Moulton said in The Burns  P137, “the action in rem is an action against the ship itself. It is an action in which the shipowners may take part, if they think proper, in defence of their property, but whether or not they will do so is a matter for them to decide, and if they do not decide to make themselves party to the suit in order to defend their property, no personal liability can be established against them in that action. It is perfectly true that the action indirectly affects them” (Chan et al 21).
Maritime liens, however, are complicated issues because of the usual conflicts of laws involved. For one, there is no single rule on what constitutes maritime liens although there are the so-called traditional maritime liens and statutory maritime liens. The former refers to liens that have become so by practice in the admiralty world whilst the latter are those which are prescribed in statutes of statutes. Under English law, for example, the traditional liens, as enumerated in the case The Ripon City  P 266 (242) (Adm) are “bottomry, salvage, wages, disbursements, liabilities, and damage” and arise automatically, ipso facto, upon the occurrence of the fact without notice or formality, remaining in and following the ship or cargo from owner to owner, including