President Jimmy Carter exercised presidential power to suspend admission of Iranians on the basis of their nationality during the Iranian hostage crisis. A constitutional challenge to his registration requirement for Iranians already in the United States was dismissed by the U.S. Court of Appeals for the District of Columbia. That court cited a Supreme Court opinion in the 1952 case Harisiades v. Shaughnessy, that "any policy toward aliens is … interwoven with … foreign relations, the war power, and the maintenance of a republican form of government. Such matters are so exclusively entrusted to the political branches of government as to be largely immune from judicial inquiry or interference."