Port state control (PSC) is an internationally agreed regime for the inspection by PSC inspectors of foreign ships in ports other those of the flag state. PSC officers are required to investigate compliance with the requirements of international conventions, such as SOLAS, MARPOL, STCW, and the MLC. Inspections can involve checking that the vessel is manned and operated in compliance with applicable international law, and verifying the competency of the ship's master and officers, and the ship's condition and equipment.
The United States is not a member of any port state control MOU. However, the United States Coast Guard verifies that all foreign vessels operating in United States waters are in substantial compliance with international conventions, as well as all applicable U.S. laws, regulations and treaties.
In 1978, a number of European countries agreed in The Hague on a memorandum for the audit of labour conditions on board vessels as to whether they were in accordance with the rules of the ILO. After the Amoco Cadiz sank that year, it was decided to also audit safety and pollution practices. To this end, in 1982 14 European countries agreed on the Paris Memorandum of Understanding on Port State Control (Paris MoU) to establish port state control. Nowadays 26 European countries and Canada are signatories of Paris MoU. PSC was a reaction to the failure of those flag states - especially flag of convenience states — that had delegated their survey and certification responsibilities to classification societies.
Modeled on the Paris MOU, several other regional MOUs have been signed, including the Tokyo MOU (Pacific Ocean), Acuerdo Latino or Acuerdo de Viña del Mar (South and Central America), the Caribbean MOU, the Mediterranean MOU, the Indian Ocean MOU, the Abuja MOU (West and Central Atlantic Africa), the Black Sea MOU, and the Riyadh MOU (Persian Gulf).
The Port State Control (PSC) makes inspection of ships in port, taken by Port State Control Officer (PSCO). Annual report of Paris MoU reported that a total of 74,713 deficiencies were recorded during port state control inspections in 2007, which deficiencies resulted in 1,250 detentions that year. Detention of the ship is the last course of action that a PSCO would take upon finding deficiencies aboard the vessel.
Courses of action a PSCO may impose on a ship with deficiencies (in order of ascending gravity) are:
Ships making a port call are usually under a specific contract, either chartered or responsible for carrying goods as a carrier. Detention may result in the ship not being able to perform the contract according to what is agreed. Ships under detention cannot continue the voyage and may not arrive at the destination port in the specific time allowed in the contract.
If, as a result of detention, the contract is discharged, it may be discharged by "frustration".
A contract discharged by frustration is well defined in Taylor v Caldwell, where the contract between Taylor and Caldwell is held frustrated. It is because the concert hall which is hired by Taylor from Caldwell is destroyed without fault of either party  and the contract is therefore discharged by frustration.
A voyage contract can be discharged by frustration if the ship is beyond the control of the party involved in the contract.
According to Texas Company v. Hogarth Shipping Corp, a voyage charter is carrying out in 1915 while the British government take control of the vessel while the vessel is in British waters. This requisition resulted in another vessel being hired to perform the contract. The court held that the original contract is being frustrated as the original vessel is beyond the control of the party involved.
The case demonstrated the contract can be discharged by frustration while the control of the subject vessel is under control of a third party which has no relation with the contracted parties.
The contract can be discharged by frustration if the detention lasts long enough for the frustration doctrine to be invoked.
In Jackson v Union Marine Insurance Co, the contract is held frustrated. When the vessel went aground and require a time of 8 months to repair the ship, the delay is too long, the cargo can be shipped by another charter in a much shorter time. The length of the delay is long enough to provoked the frustration doctrine.
The contract cannot be discharged by frustration if it is caused by self-induced detention.
The main criteria for detention is that the ship is deemed unsafe to proceed to sea and that the deficiencies on a ship are considered serious by the inspector. These deficiencies must be rectified before the ship may sail again. In the annual report of Paris MOU, it stated that the major deficiencies are:
1. Certification of crew
3. Maritime Security
4. Marine Pollution and Environment
5. Working and Living Condition
These deficiencies are the most common concern of a PSCO. When these deficiencies are clearly hazardous to safety, health, or the environment, the PSCO would require the hazard to be rectified before the ship can sail or detain the vessel or even issue a formal prohibition of the ship to operate.
As these deficiencies are self-induced by the ship operator or the ship owner, detention under PSC for the reasons listed above is not able to reach a frustration to discharge the contract on the vessel.
The contract cannot be discharged by frustration if the time under detention is not long enough to provoked the frustration doctrine.
The PSC  require a ship being detained to remedy the deficiencies which caused the detention. If the deficiencies cannot be remedied in the port of inspection, the port state would allow the ship to proceed to another port under special condition. The ship become free of detention only when all the fee induced by the inspection and detention is paid by the ship-owner.
Rationally, both the port state and the ship-owner do not want the ship to be detained for a long time. For the port state, the hazard of the ship might affect the condition of the port, and the ship-owner understand the vessel can only make money when it is sailing. Neither party would have the intention to keep the vessel being detained for an extremely long period of time. Therefore, the time of detention is normally not long enough to provoke the detention doctrine to discharge a contract.
In conclusion, a voyage contract can be frustrated when: The vessel is beyond the control of the parties in the contract. The time delayed is long enough to provoke the frustration doctrine.
Under PSC, detention is mostly caused by self-induced deficiencies which is neither unforeseeable and unexpected, and the time for detention is not likely being long enough to provoke the frustration doctrine.
Therefore, detention of a ship by PSC cannot discharge a voyage contract by frustration.