The act of state doctrine is a court-made (common law) doctrine that prohibits U.S. courts from judging the validity of the official acts of a foreign country that take place within that foreign country's borders.
In South Dakota, as in other U.S. states, the act of state doctrine is recognized as a principle of federal common law rather than state statute. This doctrine suggests that South Dakota courts, like all U.S. courts, are generally prohibited from evaluating the legality of governmental actions taken by a foreign sovereign within its own territory. The rationale behind this doctrine is to respect the sovereignty of foreign nations and to avoid conflicts in foreign relations that could arise from the judicial assessment of such actions. However, the application of the act of state doctrine is subject to certain exceptions and may not apply if the foreign act in question violates international law or U.S. public policy. It's important to note that the act of state doctrine is primarily applied in federal courts, and its application in state courts may be influenced by federal foreign policy considerations and U.S. Supreme Court interpretations.