Three main divisions. In order to discharge the duties to other nations (of so-called civilized mankind) which are imposed alike by political prudence and by international law, English criminal law has made provision for the punishment of persons who (1) commit acts of piracy or (2) commit certain breaches of the neutrality due to belligerent nations, or (3) infringe the established privileges of ambassadors sent to us by foreign governments.

Section I. Piracy

It has been said that piracy jure gentium

is only a sea term for robbery, piracy being robbery within the jurisdiction of the Admiralty. ‘If the mariners of any ship shall violently dispossess the master, and shall afterwards carry away the ship itself or any of the goods… with a felonious intention…this is robbery and piracy….’ This statement, however, is not sufficiently precise for a definition, and indeed there has not so far been given an authoritative definition of this crime. A piratical robbery is not quite the same as actual robbery; moreover, an unsuccessful attempt to commit a piratical robbery is as much piracy jure gentium as if the robbery had been actually effected. Violence is certainly essential, and therefore mere larceny will not suffice. Perhaps the best approach to a correct definition is: Any armed violence at sea which is not a lawful act of war; e.g. by mutineers on board. For a pirate must be one who may be taken to be a source of danger to the vessels of all nations; and therefore those who act solely against a particular belligerent and in the interests of the Power that is at war with it are not pirates, even though they go beyond their commission. Nor will they be, even though their action be spontaneous and without any commission at all from the Power (whether a recognized State or not) whose interests they serve. But, whatever be the precise limits of piracy jure gentium, it is at least clear that anything that does not fall within them would not be regarded as a piracy at common law.