Under the common law the shipper owes an absolute duty not to deliver for the shipment the goods of a dangerous nature without expressly giving notice that they are of a dangerous nature.
Per Pilcher, J. in Leolga Compania De Navigacion v John Glynn & Son Ltd.  2 Q.B. 374 :
It is clear that, if any real meaning is to be given to the words "lawful merchandise", which are, of course, inserted into the charterparty for the protection of the owners, the goods loaded must be such as can be loaded without breach of the law in force at the port of loading. Inasmuch as the master is under the general orders of the charterer as to where a cargo shall be carried within the charter limits, it is at least logical to suppose that the charterer undertakes that the cargo shall also be the type of cargo which can be lawfully carried and discharged at the port to which he has ordered the vessel to proceed. The purpose of the provision that only "lawful merchandise" shall be carried by the charterers would be largely nullified if all that was necessary was that the cargo could be loaded without breaking the laws of the country where it was loaded.