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 Maryland, 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 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 the judicial assessment of such actions. While the act of state doctrine is applied by federal courts, state courts in Maryland would also adhere to this principle when dealing with cases that involve the official acts of a foreign country. It is important to note that there are exceptions to the act of state doctrine, such as when a U.S. statute or treaty explicitly indicates that certain foreign acts may be subject to judicial scrutiny.