Port State Control (PSC)

Port state control is the inspection of foreign-flag ships in a state’s ports to verify that they meet the international conventions, SOLAS, MARPOL, MLC, STCW, Load Lines, and Tonnage, that bind their flag state. It is the backstop to flag-state enforcement: where the flag fails, the port state catches the deficiency. PSC operates through regional Memoranda of Understanding (Paris MoU 1982 first) that share inspection data and apply common targeting, and an officer who finds a clear hazard can detain the ship until it is rectified.