Port State Control (PSC) is the inspection of foreign ships in national ports to verify that the condition of the ship and its equipment comply with the requirements of international regulations and that the ship is manned and operated in compliance with these rules.
Many of IMO's most important technical conventions contain provisions for ships to be inspected when they visit foreign ports to ensure that they meet IMO requirements.
These inspections were originally intended to be a back up to flag State implementation, but experience has shown that they can be extremely effective. The Organization adopted resolution A.682(17) on Regional co-operation in the control of ships and discharges promoting the conclusion of regional agreements. A ship going to a port in one country will normally visit other countries in the region and it can, therefore, be more efficient if inspections can be closely coordinated in order to focus on substandard ships and to avoid multiple inspections.
This ensures that as many ships as possible are inspected but at the same time prevents ships being delayed by unnecessary inspections. The primary responsibility for ships' standards rests with the flag State - but port State control provides a "safety net" to catch substandard ships.