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 Maine, as in other U.S. states, the act of state doctrine is a principle derived from federal common law, rather than state statute. This doctrine holds that U.S. courts will not examine the validity of public acts performed by a recognized foreign sovereign within its own territory. The rationale behind this doctrine is to avoid conflict with other nations that could arise if U.S. courts were to question the legality of another nation's actions within its own borders. While the doctrine is not codified in Maine state law, it is applied by federal courts, including those that have jurisdiction over cases in Maine. The U.S. Supreme Court has affirmed the act of state doctrine in several cases, and it remains an important principle in international law and relations. However, there are exceptions to the doctrine, such as when a specific statute or treaty provides otherwise, or when the foreign act in question violates international law or fundamental human rights.