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, 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 U.S. Executives’ prerogatives in foreign affairs from being frustrated by a decision issued by U.S. Courts.
The Act of State doctrine evolved through various case laws which are discussed below. The basis of the doctrine and its exceptions are also discussed in the links below.