Foreign states are presumptively immune from suit, subject to statutory exceptions.

Commercial activity exception. The principal route. Immunity does not apply to actions based on commercial activity carried on in the forum, on an act performed in the forum in connection with commercial activity elsewhere, or on an act outside the forum in connection with commercial activity elsewhere that causes a direct effect in the forum.

Commercial is determined by the nature of the activity rather than its purpose. A state buying goods acts commercially; a state regulating does not.

Waiver, express or implied, including by agreeing to arbitration in a convention state.

Arbitration exception permitting actions to enforce agreements and awards.

Expropriation exception in narrow circumstances involving property taken in violation of international law with a commercial nexus to the forum.

Instrumentalities. Separate legal entities of a state are presumed independent, and that presumption is overcome only where the entity is so extensively controlled as to be an agent, or where recognizing separateness would work fraud or injustice.

Execution immunity is separate and narrower: property used for commercial activity in the forum may be attached, and diplomatic and central bank assets generally may not.