How ‘enemies of mankind’ shaped International Law

Written by Lia Moskov

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Did pirates “found” international law, or did states simply invent international law against them?

Before the International Criminal Court, before the Hague, before the very idea of human rights tribunals, there were pirates swinging from the gallows. Branded ‘enemies of all mankind,’ they were the first case study for what it meant to have laws that belonged not to any single nation, but to the world. Their very existence brought the question, “What happens when crime ignores borders?”

International law is the system of rule and principles that govern relations between states, IGOs and now increasingly, individuals. However, unlike domestic law, it lacks a central authority and compliance largely depends on reciprocity and reputation as there are no technical means of enforcement. When pirates were branded ‘hostis humani generis’, also known as ‘enemies of all mankind’, they were placed in an entirely new category of offenders. The phrase itself goes back to Roman law, where crimes such as piracy were considered a threat to the collective safety of empires, so much so that the ‘enemies’ were outside the protection of any state. This idea was later revived in early modern Europe in the 16th-18th centuries. Pirates were not fighting under a sovereign flag or following any laws of order, they were stateless actors yet criminals by definition. This meant that any state had the authority to capture and punish them irrespective of what crime had occurred or the nationality of the said criminal. 

This was radical at the time, up until this point most law had been strictly territorial. Pirates broke that mold. This idea foreshadowed the modern idea of universal jurisdiction, where certain crimes are considered so grave that any court can claim authority over them. In a sense, the pirate was the original template for the global criminal, as they forced the idea that some threats transcend borders and require legal collective responsibility, for example in modern systems, under the ICJ (the International Court of Justice).

To conduct a modern parallel, the concept of ‘hostis humani generis’ did not disappear with the Golden Age of Piracy, but it re-emerged in the 21st century with the Somali piracy crisis of 2005-2012. Pirates had been operating off the Horn of Africa and had hijacked commercial vessels and endangered crew through kidnappings and randoms. This triggered a legal enigma: who exactly had jurisdiction here? The Somali courts were arguably weak and western navies were reluctant to fill up their own systems with pirate trials, therefore no single state “owned” the problem. As for the response, piracy was declared a crime of universal jurisdiction. The UNSC passed resolutions authorising international navies to pursue pirates into Somali waters, trials took place not just in Somalia but also in Kenya, the Netherlands and even the United States, becoming an echo of the modern practice that any court could punish pirates as ‘enemies of mankind’. 

There is an interesting parallel to be made here, when piracy is compared to terrorism. After 9/11, terrorism was similarly framed as a borderless crime demanding global cooperation. It was said that like pirates, terrorists operate outside sovereign authority, use violence for personal means to an end and destabilise international order. This continuity raises a deeper question, do international legal normities evolve proactively through idealistic agreements, or reactively in response to threats outside state order? Whether it be pirates or terrorists, it seems that law often advances when states confront actors that defy territorial boundaries, therefore forcing cooperation where none previously existed. If a Somali pirate can be tried in a court thousands of miles from the Indian Ocean, what does this say about the future of international law? I would consider that its story is less about noble ideas and more about how humanity learns to tame those it cannot ignore.