Although not strictly part of legal principles, no mention of the IMO should omit reference to their University, based in Malmo, Sweden, where students undertake MSc programmes in several aspects of shipping and port operations.  The Institute of Chartered Shipbrokers has enjoyed close links with the WMU for many years. When legal problems arise between shipowners and those dealing with them, the international nature of shipping creates a problem of how and where to enforce a legal claim.  If the errant shipowner and the claimant are in the same country, there is no problem, normal action in the civil courts can be instituted. Where the shipowner is in a different jurisdiction from the claimant, problems arise.  The claimant may, of course, take action in the country of the shipowner but this has many problems of its own not the least of which is that some shipowners are ‘hard to pin down’   A solution to this was found many years ago, in the days of sailing ships in fact, which is why one hears the expression “nailing a writ to the ship’s mast” – this physically happened in those days.  Today it is more usual for the arrest warrant to be affixed to a bulkhead in the bridge (with sticky tape).  The point is that it is possible to arrest a ship; this is described as an action in rem (against the thing) as opposed to in personam (against the person).  It is helpful when thinking of ship arrest to imagine that it is the ship itself that has incurred the debt or caused the problem; this does not work infallibly but it does in most cases. The object of such an arrest – and frequently the mere threat of arrest is sufficient – is to obtain security for a claim. Normally the result is a dependable letter of undertaking providing both security and agreement to a particular forum – place where the legal action will take place.