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 Colorado, as in other U.S. states, the act of state doctrine is recognized and applied based on federal common law, rather than state statutes. This doctrine holds that U.S. courts will generally refrain 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 such judicial scrutiny. While the act of state doctrine is a federal principle, Colorado courts would apply it in cases where a question arises concerning the validity of a foreign state's sovereign acts. However, the doctrine is not absolute and may be subject to certain exceptions, such as when a U.S. statute or treaty explicitly indicates that the act of state doctrine should not apply, or when the foreign act in question violates international law or fundamental human rights.