As far as I can make out, the Iranian tanker Grace 1 was seized by Gibraltar whilst it was travelling through Gibraltar's territorial waters. See e.g. this article. The stated basis for the seizure was that it was suspected of violating EU sanctions by carrying crude oil to a sanctioned refinery in Syria.

What was the legal basis in international law for this? Even though the ship was in territorial waters, the United Nations Convention on the Law of the Sea specifies that vessels should have either "innocent" or "transit" passage through international straits. There are some restrictions that coastal states can impose on ships, but none of them seem to relate to carrying cargoes in violation of sanctions. As far as I know the sanctions are EU sanctions and so only relevant to domestic law and not international law.

According to Wikipedia, the UK has ratified the UNCLOS whereas Iran has signed but not ratified it. I don't know if this makes any difference.

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    @MichaelSeifert thanks, the answer to that question actually does point to the answer to mine, though it's not very explicit there (I've left a comment). I guess the options for this question are to either write a short answer, or close it with a pointer to the politics.se question. Jul 15, 2019 at 14:36
  • I've now posted an explicit answer there: politics.stackexchange.com/a/43014/4447 - while I think this is more of a law question than a politics one, there's no point in having both and the one on politics has been there longer and has more content already. I'll flag this for closure. Jul 15, 2019 at 19:38
  • This has been left open since there was already another answer by the time the flag was handled. I've cross-posted my answer now. Jul 18, 2019 at 9:07
  • I intended to post a comment, but I require 50 reputation for that, so will post my comment here. Apologies for this. This article reports: > Grace 1 was supposed to undergo maintenance before being captured, but > the latest events disrupted installation of spare parts, which > rendered the tanker incapable of undertaking a long voyage. If Grace 1 was unable to continue its journey without maintenance, it could be argued that this constitutes an emergency or distress as set out in international shipping laws, and thus its stop i
    – SayLess
    Sep 12, 2019 at 7:00

2 Answers 2


The passage is alleged to be not “innocent”

From Article 19:

  1. Passage is innocent so long as it is not prejudicial to the peace, good order or security of the coastal State.

The article enumerates a non-exhaustive list of things that are not innocent but the UK is free to make laws adding things to the list providing these are “published” (Article 21). The sanctions on Syria were published.

  • Did you mean article 19? I'm looking at un.org/depts/los/convention_agreements/texts/unclos/… - I don't see anything in section 2 of the article about being able to publish new items. Jul 15, 2019 at 21:42
  • It’s in article 21.
    – Dale M
    Jul 15, 2019 at 21:48
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    The bit titled "Laws and regulations of the coastal State relating to innocent passage"? I don't see anything that allows an arbitrary thing to be added. (h) is the closest but sanctions against another state aren't customs, fiscal, immigration or sanitary laws. Jul 15, 2019 at 21:54
  • @GaneshSittampalam sure - no doubt that will be an argument before the court
    – Dale M
    Jul 15, 2019 at 22:36
  • Is there any international court where any party to the dispute can challenge this allegation?
    – gerrit
    Jul 18, 2019 at 9:37

This is a copy of my answer to a similar question on politics.se, which I only became aware of after posting this question. My answer there is itself derived from material dug up in another answer, but it expands on the legal justification I think that material implies.

The key legal point of their justification seems to be this, from the press release.

The Grace 1 was detained last week in Gibraltar when it freely navigated into British Gibraltar Territorial Waters to a point two miles off the Eastside of Gibraltar, having previously exited the international waters of the Straits of Gibraltar, on a pre-arranged call for provisions and spare parts.

Article 18 of UNCLOS says this:

  1. Passage means navigation through the territorial sea for the purpose of:

    (a) traversing that sea without entering internal waters or calling at a roadstead or port facility outside internal waters; or

    (b) proceeding to or from internal waters or a call at such roadstead or port facility.

  2. Passage shall be continuous and expeditious. However, passage includes stopping and anchoring, but only in so far as the same are incidental to ordinary navigation or are rendered necessary by force majeure or distress or for the purpose of rendering assistance to persons, ships or aircraft in danger or distress.

Once you stop to take on supplies, it's no longer passage, regardless of whether you are in territorial waters where innocent passage would normally be allowed.

I also don't think stopping to take on supplies in itself counts as calling at a roadstead or port facility. But even if it did, "passage" only seems to apply to going to or from the place, not actually being at it. If you did choose to stop in a country's facility, you'd be placing yourself fully within its jurisdiction. There's no suggestion the Grace 1 visited Gibraltar's internal waters.

  • To me Article 18 appears designed to prevent possibly hostile ships from loitering in another country's water, not to prevent taking on supplies 'incidental to ordinary navigation'
    – steve
    Jul 20, 2019 at 16:59
  • Note that "internal" waters and "territorial" waters are quite different. As far as I can tell Grace 1 did not stop in Gibraltar internal waters.There is no right of innocent passage in internal waters, but there is in territorial waters. Jul 30, 2019 at 6:25
  • @FrancisDavey yeah, I've tried to clarify my answer to say that I think stopping even in territorial waters is a problem for innocent passage. The bit that confuses me about the Gibraltar press release is that it talks about international waters, which I would expect not to exist in that area given the strait is only 9 miles wide. Jul 30, 2019 at 6:41
  • I think your sentence "once you've chosen to stop in a country's internal waters..." is confusing because there's no argument that Grace 1 did so (I suspect the internal waters of Gibraltar are very small anyway). A map to explain how there could be international waters: gibnet.com/fish/waters.gif We aren't actually in the straight - otherwise we would be looking at completely different bits of UNCLOS of course. Jul 30, 2019 at 6:58
  • @FrancisDavey thanks, I've clarified again. That map is also very helpful. Jul 30, 2019 at 7:13

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