Enemy Of All Mankind
It was a calm night aboard HMS Plynlymon. The night watch were relaxing at their posts, listening to the quiet sound of the waters against the prow. Glancing back towards the west, Second Officer Wane thought he saw something on the horizon. He looked harder, no doubting it this time, gliding smoothly through the waters of the Carribean was another ship. Gazing through his telescope, he took a sharp breath, the ship was flying a dark flag, the personal emblem of its captain, a Jolly Roger. Wane stood and gave out the call...
"Pirates!"
Introduction
The sixteenth century was an interesting time to be a sailor. The feudal system was collapsing, the merchant class was growing and new lands, rich with gold, were being discovered thousands of miles from Europe. New technologies were being developed too; ships were getting bigger and faster, navigation was getting more accurate, cannons were more useful than ever and swords were light and cheap. All this, combined with the emerging economic philosophy of mercantilism, created an atmopshere ripe for all kinds of maritime plundering and piracy.
Of course, the threat of piracy was an old one, but in the vast new unfamiliar waters of the west indies, it became a greater problem than ever before. Pirates would attack with impunity, caring not for nationality, rank or status. Not even caring for the ships of their own country. They were a threat to be feared, and an expensive one at that. Something had to be done.
The solution, in a slightly modified form still exists today. Navies were ordered to patrol the waters in which pirates were known to operate. Ships with guns, crewed by men with yet more guns, and swords, would sail from port to port looking for any ship that might be slightly dodgy. Upon encountering such a vessel, they would signal for it to stop and prepare to be boarded. If they discovered contraband, or were attacked, the naval officers would return in kind, a battle would ensue and hopefully, provided the defence budget that year was good enough, the navy would win and the pirates would be arrested or dead. Arrested pirates could be tried and executed, and dead pirates were no problem.
Getting to the Point
There was of course a different problem. Despite the undeniable fact that many pirates were Very Bad People, they were still people. They were even citizens or subjects of the countries from which they hailed, and it was this fact that could have caused a fair amount of grief. You see, normally, if you commit a crime, one of two entities has jurisdiction to try and punish you; firstly, your own state, or secondly, the state in which you committed the crime (obviously there is no issue if you committed the crime in your own state).
Pirates, however, committed their crimes on the high seas – outside of any state's borders – and they sailed illegally under their own colours, meaning that usual laws of "flag jurisdiction"1 did not apply. So if an English ship caught a ship full of Spanish pirates and stolen French gold on the high seas, what would happen? Both Spain and France would have a claim to jurisdiction, but England would not, despite the fact that it caught them. Now, handing them over to Spain or Fance might be diplomatically difficult, the relationship between these great European powers was tense at best, odds were that at any one time, one might be at war with the other. Naturally, you do not hand over your captives to your enemy, or indeed your friend's enemy. Another question was that of what should become of the gold? If England was, for example, at war with France, it would obviously not want to give it back.
The Point
Since piracy affected everyone reasonably equally, it was in everyone's interest for something to be done. The response was, perhaps surprisingly, very simple. When pirates were caught, they were tried and executed by their captors and no-one else complained. It appeared that there was a common consensus that the captors of pirates do have jurisdiction to try them. When lawyers asked where this jurisdiction came from, they were told that pirates were hostis humani generis - enemies of all mankind – and as such were under what is known as "universal jurisdiction" that is, every country had the inherent right to try them and to sieze their plunder.
The law has remained much the same to the present day. Piracy is now defined under international law by article 101 of the Convention on the Law of the Sea and article 105 provides that:
On the high seas, or in any other place outside the jurisdiction of any State, every State may seize a pirate ship or aircraft, or a ship or aircraft taken by piracy and under the control of pirates, and arrest the persons and seize the property on board. The courts of the State which carried out the seizure may decide upon the penalties to be imposed, and may also determine the action to be taken with regard to the ships, aircraft or property, subject to the rights of third parties acting in good faith.
Which is legalese for what I have already said above. It does not make any mention of hostis humani generis but the principle still applies. Interestingly it has also recently come to be applied to other villains such as slavers, torturers, war criminals and perpetrators of genocide. These criminals are today considered to be as much as a danger to the global community as piracy was in the sixteenth century. As time goes by, it is highly likely that more will be added to the list.
Notes
1a state is usually taken to have jurisdiction over the ships that sail under its flag.
Sources
Shaw, M N International Law (5th ed. Cambridge University Press 2005)
http://en.wikipedia.org/wiki/Hostis_humani_generis
The lectures of Professor R. Piotrowicz, Professor C Harding, and M. Odello and the Seminars of N. Szablewska