Act of State

The doctrine that the courts of one country will not sit in judgement on the sovereign acts of another country performed within its own territory. The act of state doctrine prevents English courts from examining the validity of legislative or executive acts of a foreign government, even where those acts affect private rights.

In practice

The act of state doctrine may be raised as a defence in enforcement proceedings where the debtor argues that the underlying judgement or the circumstances giving rise to the debt involve sovereign acts of a foreign state. For example, a state may have expropriated property or imposed currency controls that affect the debt. The doctrine operates alongside state immunity but is a distinct principle.