Who owns the Strait of Hormuz?

The Roman legal principle actio aquae pluviae arcendae was formulated around 450 BC by the procurators (traveling Roman Magistrates), to prevent one neighbor from blocking the natural flow of a river that ran across several farms. The reason behind the rule is obvious: The river is res communes (it belongs equally to all), and one neighbor cannot be allowed to “dam up” the entire river for himself; such an action is against Natural Law and Aequitas.

This principle can, and should, be applied to the Strait of Hormuz (“the Strait”):

~ The Strait is a "Natural Waterway" running through the backyard of several neighbor States, and is therefore res communes. Of course, this argument conflicts with Iran’s claim of territorial waters, but it should be clear, at first blush, how untenable it is to argue that Iran has a superior legal right to control the Strait on the basis of it being their “territorial waters”. There are three countries bordering the Strait, namely, Iran, Oman, and the UAE, and all three of them could raise this argument. The result could easily be a situation where ships passing through the Strait might have to pay toll to all three these countries, as they could all claim the Strait as their own personal fiefdom on the basis of “territorial waters”.

~ Nations like the UAE, Saudi Arabia, Kuwait, Bahrain, and Qatar are higher neighbors of Iran with reference to the Strait, and the rest of the world are lower neighbors, all connected economically and logistically via the Strait. Iran has a legal duty, under the application of the actio aquae pluviae arcendae (and the prevailing principles of International Law) to accept the flow of shipping through the Strait from higher neighbors to lower neighbors.

~ Closing the Strait amounts to a manu facto opere (man-made work), causing economic loss and logistical damage to all neighbors.

~ This sound Roman logic is reflected in the modern UN Convention on the Law of the Sea (UNCLOS), which establishes the right of international passage through waterways like the Strait. Just like Roman Law did not allow any one neighbor to act as “owner“ of a natural waterway, UNCLOS states that "there shall be no suspension of transit passage" through international waterways like Hormuz.

~ Iran has not ratified UNCLOS, but an overwhelming majority of legal scholars (in my view, correctly) argue that the right of passage through the Strait is based on customary International Law; meaning it is a universal legal right that applies regardless of signed treaties.

Of course, the current impasse in the Strait will probably not be solved by legal arguments, but the law is clear: Iran is not, and can never be allowed to act as, the sole “owner” of the Strait, or “legal decision maker” regarding all naval traffic passing through it.

Considering the principles already laid down by UNCLOS, the international community should be ready to assist with the opening of the Strait, in accordance with overwhelming legal consensus regarding the general and irrevocable right of international passage through it.