Act of state doctrine

The Act of State Doctrine says that a nation is sovereign within its own borders, and its domestic actions may not be questioned in the courts of another nation. The doctrine is not required by international law (neither customary international law nor treaty law), but it is a principle recognized and adhered to by United States federal courts. Its aim is not to protect other nations' sovereignty by intervention from the U.S. but rather to protect the US Executive's prerogatives in foreign affairs from being frustrated by a decision issuing from U.S. Courts.
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This doctrine says that a nation is sovereign within its own borders, and its domestic actions may not be questioned in the courts of another nation.