Iran’s Disingenuous Approach To Maritime Law

A starboard beam view of an Iranian Alvand-class frigate underway in 1988.

PH1 Alex Hicks / U.S. Navy

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A starboard beam view of an Iranian Alvand-class frigate underway in 1988.

The illegal seizure of the Maersk Tigris illustrates Tehran’s desire to pick and choose what international rules it follows.

Iran’s seizure of the MV Maersk Tigris underscores the importance of a stable rule of law in the oceans, and the dangers of allowing one state to attempt to alter them for its own benefit.

The ship, boarded and taken by force to Bandar Abbas on April 28, was turned over to the Iranian Revolutionary Guard to fulfill a court judgment in favor of Iran Ports Authority. It should surprise no one that this vacuous legal rationale is incompatible with the rules set forth in the customary international law of the sea and reflected in the Law of the Sea Convention, or LOSC.

The Strait of Hormuz is 21 nautical miles in width, and constitutes the territorial sea of Oman and Iran. The Maersk Tigris, sailing under the flag of the Republic of the Marshall Islands, was captured in the Strait in an area overlapped by Iranian territorial waters. Under the LOSC, the parts of the territorial sea that are used for navigation and that connect one area of the high seas or exclusive economic zone (EEZ), in this case the Persian Gulf, with another area of the high seas or EEZ, here the Arabian Sea, form a strait used for international navigation. Straits have a dual nature, as they are simultaneously territorial seas of the affected coastal states as well as for international navigation.

The regime of transit passage applies in such straits, and Maersk Tigris enjoyed unimpeded transit through the strait. Unlike in innocent passage, submarines may travel submerged and aircraft may overfly the strait while in transit passage. Notwithstanding the regime of transit passage, article 42 of UNCLOS authorizes the coastal state to adopt laws for regulation of commercial maritime traffic, vessel discharge of oil, prevention of illegal fishing, and customs and immigration matters. With the limited exception for violations that may cause or threaten to cause “major damage” to the marine environment of the strait, Iran may not enforce its laws against foreign flag vessels transiting the strait. In any case, such laws cannot have the “practical effect of denying, hampering, or impairing the right of transit passage.”

Outside of straits, navigation in the territorial sea must be in innocent passage. Only surface ships and submarines transiting on the surface enjoy the right. Article 28(2) of the LOSC states that the coastal state may not arrest a foreign ship for any civil proceeding, except for liabilities incurred by the ship itself, and then only during the course of or for the purpose of the specific transit.

Iran has signed, but not ratified the LOSC. As a signatory to the treaty, however, Tehran is obligated not to undermine its “object and purpose.” (This responsibility is set forth in the Vienna Convention on the Law of Treaties.) The essential bargain in the LOSC was expansion of the customary territorial sea from 3 nautical miles to 12 in exchange for the recognition of the right of transit passage through straits. Yet Iran claims that the terms of the treaty are “merely a product of quid pro quo,” and therefore nonparties to the treaty, such as the United States, do not enjoy the right of transit passage. The United States counters that although the regime of transit passage through straits is reflected in LOSC, it springs from customary international law and is therefore already binding on all states.

The legal right of passage through the Strait of Hormuz is tied to the collateral issue of the width of the territorial sea of Iran and Oman. If Iran expands its territorial sea from the 3 miles to 12, it must accept transit passage as part of the overall package deal. If there is no transit passage in the Iranian territorial sea, then Iran is permitted to claim only a 3-mile territorial sea. High seas freedoms would apply beyond that limit.  

Iran’s current claim of a 12-mile territorial sea means that other nations are entitled to exercise freedom of navigation and enjoy transit passage through the strait. Otherwise, ships and aircraft would still have a right to the historic antecedent of general high seas freedoms, which is even more permissive. Either way, the law of the sea recognizes unimpeded passage. Instead, Iran has sought to preserve the navigational regime of innocent passage.

Even assuming that the regime of innocent passage applied to the Maersk Tigris, however, Iran’s seizure was still unlawful. Tehran is trying to replace the package deal of the law of the sea with a cafeteria-style selection of favored provisions and rejection of others that benefit and protect the international community. This conduct is of a familiar style and pattern for the regime in Iran, and an indictment on its ability to implement international law in good faith.

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