Iran and the Strait of Hormuz: some initial thoughts

Written by

Iran has repeatedly threatened to close the Strait of Hormuz in response to any oil embargo or other unilateral sanctions taken against it. The Strait of Hormuz, depending on the reports you read, is at its narrowest somewhere between 17 and 30 nautical miles wide. The bordering States Oman and Iran both assert 12 nautical mile territorial seas. However, the deep water channels that are safe for tankers, used under an International Maritime Organization traffic separation scheme, are only two miles wide each. The outbound lane from the Persian Gulf passes through waters off Oman, the inbound lane through Iranian territorial waters. (Please correct me if I have any of this factual material wrong.)

What legal regime applies to the route through Iranian territorial waters? The ordinary starting point would be that a State may temporarily suspend innocent passage its territorial waters, without discrimination, for essential security reasons (Article 25(3), UN Convention on the Law of the Sea). However, as Hormuz is a strait used for international navigation, Iran lacks that ordinary power.

Under UNCLOS, where a strait is used for international navigation and there is no equally convenient route through open high seas waters, then “all ships and aircraft enjoy the right of transit passage, which shall not be impeded” (Art. 38(1)). This would seem decisively against Iran, but for the fact it is only a signatory to the UN Convention on the Law of the Sea and has never ratified it. The precise legal regime applying to Iran and the Strait of Hormuz is thus open to debate.

Some States, especially the US and UK, contend the UNCLOS regime of unimpeded transit passage is customary international law. The alternative is that outside UNCLOS there is only a customary international law right of non-suspendable innocent passage. The Corfu Channel case established in 1949 that warships, and a fortiori merchant ships, have a right of innocent passage through international straits which the coastal State may not suspend.

It was certainly held under the Corfu Channel case that in a time of heightened tensions Albania would have been entitled to regulate (though not prohibit or effectively nullify) the passage of warships through its waters. (See further the discussion in Churchill and Lowe.) Thus it is clearly arguable that under the non-suspendable innocent passage regime a coastal State retains its right to prevent non-innocent passage by individual foreign vessels; while under the UNCLOS transit passage regime it would lack any such rights of enforcement (though it would retain the right to formally regulate certain matters).

Thus, there is some basis for an argument that Iran could seek to restrictively regulate passage through its territorial sea short of suspending innocent passage – provided that as a matter of custom the Corfu Channel and not the UNCLOS rule applies.

However, in the comments to Sahib Singh’s recent post on Iranian sanctions Dan Joyner raised the question whether Iran could take countermeasures in the Strait in response to illegal interventions against its nuclear programme. Rather than close the Strait, Dan suggested Iran might be justified in seizing and confiscating vessels of the nationality of the States responsible for various illegal interventions against its nuclear programme (presuming these acts could be proven the responsibility of Israel and the United States).

Ordinarily, under the ILC Articles on State Responsibility, countermeasures must:

  • be targeted only against the responsible State;
  • be preceded by an offer to negotiate;
  • consist only of the injured State withholding performance of one or more international obligations owed to the responsible State;
  • be proportionate and readily reversible; and
  • not involve the use of force.

Technically, seizing individual vessels under Dan’s scenario would not involve closing the Strait. Could it be described as suspending the right of innocent passage of certain targeted States? Perhaps, though I have some (possibly formalistic) qualms about the idea that suspending a freedom from interference can create a positive right to interfere. That aside, would seizing merchant vessels involve a prohibited use of force under the UN Charter? The majority view among scholars would appear to be that such a “police action” is not usually tantamount to a use of force (see e.g. Guyana v. Suriname), though much might depend on how such an interdiction operation was carried out.

The suggestion some vessels could be seized as a countermeasure is thus not implausible, but the real question would be sufficient proof of attribution of the complained of conduct to the targeted States.

Finally, one might note that actually closing the whole of the Strait by force could constitute a blockade of the ports of Kuwait, Qatar, Bahrain, the United Arab Emirates and Iraq. This would appear to be a prima facie act of aggression against these States as the General Assembly’s Definition of Aggression (UNGAR 3314) includes blockade of ports under Article 3(c). Such an act of aggression would, at a minimum, justify Security Council intervention though we could debate what other action might be permissible in such a case.

This is far from a fully developed analysis, so thoughts are welcome. My apologies if my replies to comments are less than timely.

Print Friendly, PDF & Email


No tags available

Leave a Comment

Comments for this post are closed


Dan Joyner says

February 2, 2012

I really appreciate Douglas including a discussion of my previous comments on this issue in his post. And let me say before proceeding that the additional law of the sea material in Douglas’ post is extremely valuable and interesting.

After my original comments in response to Sahib Singh’s post, Douglas and I had an email exchange about them, and I found his comments to be insightful as usual, and helpful to me in thinking through this little thought experiment. I won’t say that the hypo I proposed (i.e. Iran seizing private vessels owned by U.S. or Israeli companies as a lawful countermeasure in response to illegal U.S. and Israeli actions against Iran, e.g. the introduction of the Stuxnet virus and the killing of Iranian civilian nuclear scientists in Iran) is undoubtedly lawful. But I would argue that if Iran decided to take this course, they would have a persuasive case for legality as a countermeasure under the ILC Draft Articles on State Responsibility.

I would note that the official commentary to Article 49 of the Draft Articles states:

“Article 49 describes the permissible object of countermeasures taken by an injured State against the responsible State and places certain limits on their scope. Countermeasures may only be taken by an injured State in order to induce the responsible State to comply with its obligations under Part Two, namely, to cease the internationally wrongful conduct, if it is continuing, and to provide reparation to the injured State.”

A seizure policy in the Strait as I have described it, could be targeted specifically to incentivize the U.S. and Israel to cease their internationally wrongful conduct, as it would introduce risk into U.S. and Israeli shipping commerce, and thus undoubtedly negatively affect the economies of the U.S. and Israel, and would thus put economic pressure on them. It would dually serve to provide a source of reparation for Iran and for the families of the dead nuclear scientists. The policy would be proportionate to the international wrongs, and could of course be quickly ceased as soon as the U.S. and Israel came into compliance with international law and ceased their internationally wrongful acts. And in my view, as supported by Douglas’ analysis, such seizures would not be classifiable as international uses of force, and thus not prohibited as countermeasures for that reason.

So again, while I won’t say it’s a home run, as far as I can see this would be a fairly strong argument. I welcome comments and further discussion.

jpaust says

February 3, 2012

I suspect that at some point an Iranian vessel would try to use armed force and that, in response, there would be a devastating use of armed force in self-defense. It may satisfy the principle of proportionality to engage many Iranian naval vessels and short batteries, etc. in order to protect a naval fleet in the area that had one of its vessels or one of its country's flag vessels under attack and that had used measures of self-defense -- because of the predictability of an Iranian escalation of force against the naval fleet. Once it starts .....

Arman Sarvarian says

February 15, 2012

A few thoughts on this interesting discussion:

1. Concerning the fact that Iran is a signatory only to the UNCLOS, is it arguable that non-compliance with Art. 38(1) could constitute a breach of Art. 18(a) VCLT? To run this argument, it would need to be shown that the specific act defeated the 'object and purpose' of the UNCLOS. Would that object and purpose be found in the preambular reference to 'the peaceful uses of the seas and ofceans' and 'peace, security, co-operation and friendly relations among all nations in conformity with the principles of justice and equal rights'? A challenging argument, perhaps, as it would have to be shown that transit passage is so fundamental to the UNCOS regime that it is its very object and purpose.

2. What would be the precise differences between the form of interdiction or blockade that Iran would implement in the Homuz Strait? Clearly, it could only be targeted against US and Israeli (military?) vessels to qualify as a countermeasure. However, if the aim of the suspension of innocent passage is the cession of the IWA and the inducement of reparation, how would 'proportionality' (Art. 51 ASR) be assessed in the following scenario. The IDF has conducted an air strike (successfully or not) against Iranian nuclear installations with Iran claiming (accurately or not) that a certain number of scientists and other non-combatants were unlawfully killed. The IDF announces that it will not conduct any further combat missions against the installations. Iran, invoking a countermeasure under the conditions specified under Art. 52 ASR (query whether Chapter II ASR as a whole reflects CIL), blockades the Strait targeting all US and Israeli (and UK?) vessels (particularly oil tankers). Given the potentially enormous financial implications of even a temporarily successful blockade, would it be commensurate to the deaths of the civilians? How to assess the value of those lives (human rights jurisprudence?)?

3. Dispute resolution: could this hypo be tested in adjudication? Iran's non-ratification of UNCLOS probably rules out Annex VII but, if the VCLT argument runs above, perhaps its Art. 66 procedure could be pursued.

Sahib Singh says

February 16, 2012

Doug - thanks for this. I had been meaning to speak to you about it at some point. For what it is worth I think there are three legal questions that need to be teased out:

(1) Does Dan's hypothetical interception and seizure of selected flag ships constitute a "hampering" or interference from that prohibited by Article 44 UNCLOS?

(2) Or does Dan's hypothetical in fact amount to more than an interference and rise to the standard of suspension (albeit selective) of transit passage, within the meaning of the second sentence of Article 44?

(3) Given the nature of the specific obligation being breached by Iran, under (1) and (2) above, as a form of countermeasure does either specific rule in fact preclude recourse to countermeasures under general international law?

For what it's worth, I think there is an arguable case that if Iran's actions amount to a suspension, there is an arguable case that it would not be a permissible countermeasure in accordance with the wording of Article 44 (second sentence). Countermeasures, under general IL, may arguably be precluded. This becomes an infinitely more complicated question, when we consider the exact contours of the customary law of transit: it strikes me that we could find numerous examples that would render the second sentence of Article 44 as being too severe and custom did not intend to derogate from the general custom on countermeasures (an easier issue to rebut in the case of treaty provisions).

Small thoughts Doug - would be interested to know if I have not formulated the issue correctly.


Douglas Guilfoyle says

February 16, 2012

Thank you all for the comments. I can't answer every point (mostly for reasons of time), but touching on a number of comments I'd suggest:

(1) As a non-signatory to UNCLOS Iran is prima facie bound only by the less stringent Corfu Channel rule and not Arts 38 and 44 UNCLOS. (Unless you can prove transit passage is now custom.)

(2) If Art 44 did apply, Sahib is raises a good question.

It is a tricky point in general whether you can use countermeasures to suspend an obligation not to interfere with foreign shipping and thereby gain a right to interfere with foreign shipping. (Some have argued you can, I have doubts.)

More narrowly, I am not sure I have an answer to Sahib's specific question: does Art. 44 on its face preclude taking countermeasures that would breach it? Obviously, international law does contain regimes with their own 'internal' rules on state responsibility that exclude the general rules. UNCLOS would normally be thought of as a self-contained regime vis-a-vis the rules of State responsibility; but that does not answer the question whether certain obligations falling short of jus cogens may nonetheless be of such a character that they cannot be suspended as a countermeasure.

(3) On Arman's VCLT Art. 18(a) argument - it's an interesting idea which might gain some traction from the idea that transit passage was meant to be the pay-off for the 12 nm territorial sea rule in UNCLOS. (That is, wider territorial seas effectively 'enclosed' some straits.) Iran has asserted a 12 nm sea (the benefit), but not taken the rest of the package (the burdens). I still think it would be a hard argument to make. As UNCLOS was negotiated as a single 'package deal' it is harder to tease out which components are 'vital' to its object and purpose. Thus there is a greater than usual risk of Art. 18(a) arguments shading towards binding mere signatories as if they were parties bound by the whole convention.

Dan Joyner says

February 17, 2012

Very interesting follow up discussion here. To Sahib's question about Article 44 of the UNCLOS, and again assuming that it did apply to the situation (I agree with Douglas that it doesnt apply to Iran), my own view would be that Article 44 isnt part of a UNCLOS-specific state responsibility regime that somehow opts out of the general rules on state responsibility. It appears to me to simply be a specific secondary rule contained in the UNCLOS, the breach of which could be justified by a lawful countermeasure pursuant to the general rules of state responsibility in CIL. If we were to take a less restrictive view toward secondary rules in regime specific treaties like the UNCLOS, it would seem to me that the general rules on state responsibility would almost never apply. I would think that a regime-specific rule on state responsibility would, in a sense, bear the burden of clarity that it was in fact a specific rule opting out of the general rules on state responsibility in CIL, and that most secondary rules in treaties, including UNCLOS Article 44, will not meet this burden.

martin Fink says

February 27, 2012

Just adding to the discussion that the US seems to base its arguments to keep the Straits open on the general basis of freedom of navigation (FON), rather than the more technical approach of the transit or innocent passage regime. Apart from the question whether or not Iran can close the SOH, for the opposite side, I guess another question should than be whether the principle of FON in the case of the SOH can legally be sufficient to force oneself to get from one high sea / EEZ to the other. Takes us back to extension of the TTW-fears to which the transit passage regime was supposed to be the solution, really. So, Iran appears to argue on legal technicalities (leading to that oil transport for some nations will endanger the security and therefore is not innocent), while the US takes the broad principle approach. I haven’t read anything yet from either side that counter each others’ arguments.