UN Convention on the Law of the Sea

Iran's Persian Gulf Strait Authority has charged transiting vessels since the spring, a practice Article 38 of this convention prohibits outright: straits used for international navigation carry a guaranteed right of transit passage, with no toll and no prior authorisation. Iran has never ratified the convention, so its own courts owe Article 38 no domestic force, and its blockade enforcement widened past the strait itself into the Arabian Sea by 27 April 2026, when Central Command's intercept tally reached 38 vessels.

By 16 July the dispute had moved from paper to boarding parties: US Marines began physically stopping ships, redirecting four and disabling one within three days, closing a vessel-renaming loophole electronic tracking alone had missed. No arbitration has yet tested Article 38 against Iran's toll; enforcement, not adjudication, is settling the dispute in practice.

The Islamabad Memorandum of Understanding banned Hormuz tolls for 60 days from 17 June 2026, then handed collection to a joint Iran-Oman body invoking this convention's Article 26(2), which permits coastal states to charge for specific services rendered, a narrow carve-out from the general ban on strait fees. Foreign Minister Araghchi confirmed the same day that charges would resume once the window lapsed, and Iran's Persian Gulf Strait Authority kept operating under the new label.

Three days later Iran made insurance compulsory on every Hormuz transit, currently free but with fees reserved from August, exploiting the same 60-day gap to build the infrastructure the moratorium was meant to prevent. Whether a flat per-vessel charge qualifies as a specific service under Article 26(2) remains legally untested.