The End of Colonial rule was one of the great achievements of Europe. Colonies are territories which have a different legal status from the land surrounding it. When the Roman Emperor Caracalla (211-217) decided that all persons living within the borders of the Roman state were Roman citizens, he eliminated the difference between a colony and the rest of the country (Constitutio Antoniana 212AD). A colony was a roman legal institution (established according to ius italicum). It was a settlement of Roman citizens (often connected with the army) which followed Roman Law, independently of the area around it. Many cities were proud to be colonies. To this day the city of Köln, Cologne, in Germany retains the name derived from Colonia Claudia Ara Agrippiniensium. Lyons in France was also created as a Roman colony (Lugdunum). London was also founded as a Roman settlement, though may not have been a colony. There are many others throughout Europe and the shores of the Mediterranean.
Today we consider a colony as a distant self-governing but not independent territory. We also consider colonists as persons who bring a new legal structure within another territory. These are ancient concepts and require a Roman solution: equality.
The emperor Caracalla put an end to such chaos in 212AD. He decided that all inhabitants within the borders were simply roman citizens (Justinian, Digest 1.5.17). Soon afterwards, the idea of eliminating contradictory local laws became central to Roman legal thought. The result was the publication of the codex of Roman Law in Constantinople in 531-534. It established equal treatment among persons and territories: no more exceptions among nationalities and specific territories. All were equal before the law.
The problem today stems from the barbarian invasions. These late antique movements of non-Roman peoples brought about the fall of the Western Roman Empire and the proliferation of law codes. Each group of people was governed by different laws based on their background. It almost reminds one of Apartheid in South Africa: each category had its own rules, privileges, and duties.
The French King Louis XIV tried to reduce the differences in regional laws in France by introducing a unified legal system, the Code Louis, in 1667-1670 (on which the Code Napoleon was later modelled). The Holy Roman Empire was a jungle of legal codes and statutes from its inception in 800 until its collapse in 1804. Spanish law was based on seventh century Visigoth law, in the form of the Fuero Juzgo, until the nineteenth century. The European colonial powers had contradictory legal systems when they started colonizing territories beyond Europe.
Equality before the law for all citizens was not exported by Europeans. It was not present in Islamic law either since non-Muslim communities could administer themselves according to their custom if they paid a special tax for non-Muslims (e.g. the emirate of Cordoba or the Turkish millet).
Caracalla introduced the modern notion of equality, by abolishing the special status of ‘colony’. The principle adopted is the following: 'Libertas est naturalis facultas eius quod cuique facere libet, nisi si quid vi aut iure prohibetur.' (Justinian, Digest 1.5.4 = Florus Institutes 9). 'Freedom is the natural capacity which allows one to do something to someone else, unless some other force or law forbids it.' If the law code is unique, it is easier to guarantee such freedom.
Multiple levels of legal codes and jurisdictions meant the proliferation of injustice. Ironically, Caracalla is telling us that federal structures as well as loose legal unions lead to injustice. They are choked by the contradictory decisions of the courts and the inevitable arbitration of supreme courts. Courts of appeal are also a colonial problem. When classical Athens in the golden age of classical democracy imposed that all appeal cases should be held in Athens instead of the local courts of the allies, it did not propose a common law code for all but considered the local courts as inferior to those of Athens. This was a two tier system: a superior one in Athens and an inferior one among allies.
Caracalla’s push for equality was probably not inspired by philanthropy. The aim was efficiency. If the same law is applied to all citizens in all areas of a country, it is easier to establish who has broken the law. The colonial spirit cherishes the proliferation of law codes, as the barbarians did in the 4th -7th centuries. The late-Roman ideal was equality before a single law code for all inhabitants of a country. This was the message that Justinian (527-565) delivered when he published the Codex of Roman Law in sixth century Constantinople.