Does Iran have any conceivable case for seizing the Maersk Tigris?  The short answer is “no.” The slightly longer answer might be “absolutely not” or “under no circumstances.”

Iran is claiming a decade old cargo dispute as the basis for seizing the ship. Admiralty law does allow a nation to arrest a foreign ship for maritime liens resulting from the sort of cargo dispute existing between Maersk and an Iranian shipper.  So far so good. The problem is that the arrest of the ship in “innocent transit” is generally not allowed.  The ship needs to be in port. More than that, the ship arrested has to be the ship against which the claim was filed. The Maersk Tigris  was not that ship.  Iran cannot simply go after any ship operated by Maersk.

The larger issue may be that the Iranians did not seize a ship that is owned by Maersk.  The Maersk Tigris is actually owned by a private equity fund, Oaktree Capital Management, and is chartered to Maersk.   The ship is not Maersk property so it cannot be seized to settle a claim against Maersk.

For a more detailed discussion of the case, Eugene Kontorovich, a professor at Northwestern University School of Law, has an excellent summary in today’s Washington Post — Iran’s legal claims for seizing the Maersk Tigris.

So why did the Iranians get the seizure of the ship so wrong?  In the realm of wild speculation, what seems to me to be the most reasonable explanation was that suggested in a comment by Louis Cohen on a previous post.   It is possible that the Revolutionary Guard got a bit over zealous.  The week prior to the seizure, a US aircraft carrier group blocked an Iranian naval convoy suspected of carrying weapons bound for Shiite rebels in Yemen.  An Iranian Revolutionary Guard commander may have decided to engage in a bit of free-lance gunboat diplomacy in relation.