Roman Sea Law

Roman Sea Law defined the Use of the Sea and how commerce and shipping should be conducted.
It was based on the much older Rhodian Sea Law.

‘Res Communes Omnium’ (Things common to all)
- The Air, Running Water and the Sea were classified under Roman Law as things common to all, and could not be privately owned.
‘Mare Nostrum’ (Our Sea)
- The Roman Empire controlled all the coasts of the Mediterranean Sea, and therefore considered it to be a Roman Sea.
‘Mare Liberum’ (Free Sea)
- In the Law of the Classical World, the High Seas meaning the Oceans, Seas and Navigable Waters, were outside of National Jurisdiction.
Mare Clausum (Closed Sea)
- Between November and March the Seas were considered too dangerous to navigate safely, and were officially closed. The term ‘Mare Clausem’ is still used in International Law today to mean a closed Sea.
- ‘Mare Clausum’ was later used by the Republics of Genoa and Venice, and later still by Portugal and Spain, to seize foreign vessels sailing on their Trade Routes. ‘Mare Clausem’ was challenged by the Dutch who insisted on ‘Mare Liberum’ to break the Portuguese Monopoly. In 1702 CE the argument was finally resolved by the introduction of a ‘three mile limit’ around coastlines, which was the range of a canon shot.
Septem maria
- According to Pliny the Elder (23-79 CE) in Historia Naturalis chap. 16, the Seven Seas referred to the seven lagoons where the river Po discharged into the Adriatic.
- However, to the Ancient Greeks the Seven Seas were: The Aegean, the Adriatic, the Black Sea, the Red Sea, the Caspian Sea and the Persian Sea (Persian Gulf).

Rhodian Sea Law
- The Sea Laws of Rhodes were a collection of Maritime Laws which regulated Commerce and Shipping.
Digest of Justinian (529-533 CE)
- The Rhodian Sea Law was mentioned in a document from the Byzantine Empire known as the Digest of Justinian.
- This was collated into three sections, with section III referring to Maritime Law and the Lex Rhodia.