Hormuz Strait Blockade by Iran: Legal or Illegal?

The Hormuz Strait blockade by Iran is not realy illegal under international law, but it is not entirely legal as well. The territorial waters are differentiated from internal waters. Hormuz strait is an example of territorial waters, whereas Suez Canal is an example of internal waters. The state controlling the internal waters can exercise full sovereignty over the internal waters subject to treaty commitments (if any). The general principle of servitus juris publici voluntuaria (akin to easementary rights) restricting sovereignty of the states over their internal waters to allow transit passage to international ships has not been upheld by ICJ. Suez Canal allows transit passage vide the 1888 Convention of Constantinople inspite of sovereignty assertion of Egypt over Suez Canal.

In case of territorial waters, United Nations Convention on the Law of the Sea (UNCLOS) creates restriction of innocent passage in case of territorial waters, which is also well recognised under international customary law vide Corfu Channel case. This restriction is also honoured by Iran. However, Hormuz Strait is a special case of territorial waters. The difference is that the territorial waters here is a strait connecting Persian Gulf to the Gulf of Oman. Both Iran and Oman have claim over 12 nautical miles from their respective baselines into the Hormuz Strait. In fact, their claim overlap over a stretch of 1 mile at the narrowest stretch on Hormuz Strait, which they have settled in 2015 Maritime Boundary Limitation Agreement.

Part III of UNCLOS deals with straits used for international navigation connecting a high sea/exclusive economic zone to another high sea/exclusive economic zone. Article 38 creates a restriction of right of transit passage on the sovereignty of adacent states in whose territorial waters the strait lies. This is, in a way, the creation of an easementary right of way. However, this right is not customary in nature like the easement by prescription. It is, at best, the easement by grant very much like in the case of internal waters. That is, if a state has not signed UNCLOS, it is not bound by the right of transit passage. Iran has signed UNCLOS, but it has not ratified it. In other words, the grant is not complete.

However, Oman has both signed UNCLOS and also honours the right to transit passage. Interestingly, most of the deep navigation channels lie in the territorial waters of Oman, and the ships have also been using Omani waters to transit since April, 2026, and even earlier. However, Iran is charging fees also from those ships that pass through Omani waters as a corollary to the Hormuz Strait blockade by Iran. Iran and Oman have also started discussing the modalities of controlling the right of transit passage through the levy of tariffs.

The above is an interesting scenario. Intitutively, the right of transit passage through a strait should be natural, but the international law favours the sovereignty more than rights. It, as already stated, just doesn’t recognise the states as being under servitude vide servitus juris publici voluntuaria (an easementary right is the imposition of servitude on the owner). However, as a corollary to the Hormuz Strait blockade by Iran, it is also levying tariff on those ships that are passing through Omani waters. Next I discuss the right of Iran to levy tariffs to grant the right of transit passage not only in its own waters but also Omani waters.

Hormuz Strait Blockade by Iran: Right to Levy Tariffs

Levy of tariffs, as a corollary to the Hormuz Strait blockade by Iran, is more a political question than a legal one. When Nasser nationalized Suez Canal, there was a strong opposition to it from France and Britain, but their empires were falling. The new entrants; i.e, the US and USSR; forced France and Britain to a humiliating exit not only from Suez Canal but also from the super power status in geopolitics.

The article 1 of 1888 Convention of Constantinople clearly mentions the free use of the canal. It obviosuly means the free right of transit passage. However, it was intrepreted to mean politcally free, not financially free. The United Nations Security Council (UNSC) Resolution 118 provided for the levy of tariff on the basis of agreement of parties. The main obective of the resolution was to legally recognize the right of transit passage. The question of tariff was secondary.

ARTICLE I
The Suez Maritime Canal shall always be free and of commerce or of war, without distinction of flag.
Consequently, the High Contracting Parties agree not in any way to interfere with the free use of the Canal, in time of war as in time of peace.
The Canal shall never be subjected to the exercise of the right of blockade

It should be noted that Suez Canal is an artifiical canal albeit built by modification of natural features; i.e, Lake Manzala, Lake Timsah, Great Bitter Lake, and Little Bitter Lake. Since it is a modification of natural features, Suez Canal is not owned by the Egyptian government. Egyptian government only manages it through the Suez Canal Authourity, which replaced Universal Company of the Maritime Canal of Suez, owned by France and Britain. The tolls are levied to cover continuous dredging and maintenance, navigation aids and safety systems, pilotage and traffic management, lighting, mooring, and emergency services, etc.

There is no fundamental difference between Suez Canal and Hormuz Strait. Both are politically obliged to grant free right of transit passage. In both the cases, financial cost is secondary and based on the agreement of parties. The only difference is the current discriminatory practices of Iran in granting right of transit passage. But, of course, this can get resolved in negotiations. The article 42 of UNCLOS anyways also gives enough leeway to the bordering states to levy tariffs.

Article 42
Laws and regulations of States bordering straits relating to transit passage

Subject to the provisions of this section, States bordering straits may
adopt laws and regulations relating to transit passage through straits, in
respect of all or any of the following:
(a) the safety of navigation and the regulation of maritime traffic, as provided in article 41; (b) the prevention, reduction and control of pollution, by giving effect to applicable international regulations regarding the discharge of oil, oily wastes and other noxious substances in the strait; (c) with respect to fishing vessels, the prevention of fishing, including the stowage of fishing gear; (d) the loading or unloading of any commodity, currency or person in contravention of the customs, fiscal, immigration or sanitary laws and regulations of States bordering straits.

The real question, as I said, is a political one. If politics favours Iran, Oman will also follow suit and join Iran in levying tariffs. Whether politics favours Iran or not is not to be discussed here. I will only reiterate what I said in one of my tweets that the real contentious issues in US-Iran negotiations are enrichment rights of Iran and war reparation, not Hormuz Strait blockade by Iran.

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