The UNCLOS distinguishes three scenarios: rules applicable to all kinds of vessels, those applicable to commercial activities carried out by State or merchant ships, and those applicable to warships and ships of State used for non-commercial purposes.
In all, about 15 articles address this matter, which is often sensitive: it in fact involves both the exercise of freedom for navigation (the oldest principle to have been established in the law of the sea, to the point of becoming its matrix) and State sovereignty, an equally ancient principle. The aim is to reconcile these two positions.
The intensity of maritime traffic in the Mediterranean calls into question the principles of innocent passage and free circulation with regard to the conservation of particularly sensitive areas such as international straits, petrochemical installations, large ports etc. Following the disaster of the Erika and especially that of the Prestige (off the coasts of Galicia), jurisdictionalisation has been seen as a means of limiting the possibly negative effects of these principles (France's Ecological Protection Zone, for example, was a direct consequence of the Prestige oil spill, Cf. Offshoots of the EEZ). Growing numbers of controls conducted by port States is part and parcel of this same trend. Finally, the joint proposal of France and Italy, to which the International Maritime Organization agreed in 2011 , to confer on the Strait of Bonifacio the status of a Particularly Sensitive Sea Area (PSSA), may offer an example of an innovative attempt to introduce instruments of a different legal kind to help protect a given area.
 UNCLOS, part II, section 3. Article 19 states that "passage is innocent so long as it is not prejudicial to the peace, good order or security of the coastal State. Such passage shall take place in conformity with this Convention and with other rules of international law".
 IMO Marine Environment Protection Committee (MEPC) – 62nd session: July 11th to 15th, 2011: http://www.imo.org/MediaCentre/MeetingSummaries/MEPC/Pages/MEPC-62nd-session.aspx