Citizenship of the United States
A person who is considered a citizen by more than one nation has "dual citizenship". It is possible for a United States citizen to have dual citizenship; this can be achieved in various ways, such as by birth in the United States to a parent who is a citizen of a foreign country (or in certain circumstances the foreign nationality may be transmitted even by a grandparent) by birth in another country to a parent(s) who is/are a United States citizen/s, or by having parents who are citizens of different countries. Anyone who becomes a naturalized U.S. citizen is required to renounce any prior "allegiance" to other countries during the naturalization ceremony; however, this renunciation of allegiance renunciation of citizenship to those countries.
United States nationality law
Based on the U.S. Department of State regulation on dual citizenship (7 FAM 082), the Supreme Court of the United States has stated that dual citizenship is a "status long recognized in the law" and that "a person may have and exercise rights of nationality in two countries and be subject to the responsibilities of both. The mere fact he asserts the rights of one citizenship does not, without more, mean that he renounces the other", "Kawakita v. U.S.", 343 U.S. 717 (1952). In "Schneider v. Rusk", 377 U.S. 163 (1964), the U.S. Supreme Court ruled that a naturalized U.S. citizen has the right to return to his native country and to resume his former citizenship, and also to remain a U.S. citizen even if he never returns to the United States.