Artikel 15

Where, in virtue of a treaty, convention or agreement, a Contracting State has granted special rights to another State within a defined area in any of its maritime ports for the purpose of facilitating the transit of goods or passengers to or from the territory of the said State, no other Contracting State can invoke the stipulations of this Statute in support of any claim for similar special rights.
Every Contracting State which enjoys the aforesaid special rights in a maritime port of another State, whether contracting or not, shall conform to the provisions of this Statute in its treatment of the vessels trading with it and their cargoes and passengers.
Every Contracting State which grants the aforesaid special rights to a non-Contracting State is bound to impose, as one of the conditions of the grant, an obligation on the State which is to enjoy the aforesaid rights to conform to the provisions of this Statute in its treatment of the vessels trading with it and their cargoes and passengers.